Merge branch 'master' into working

README.md

@@ -9,11 +9,12 @@ library    | lastest version | category | description
 **stb_image.h** | 1.46 | graphics | image loading/decoding from file/memory: JPG, PNG, TGA, BMP, PSD, GIF, HDR, PIC
 **stb_truetype.h** | 0.9 | graphics | parse, decode, and rasterize characters from truetype fonts
 **stb_image_write.h** | 0.95 | graphics | image writing to disk: PNG, TGA, BMP
+**stb_image_resize.h** | 0.90 | graphics | resize images larger/smaller with good quality
 **stretchy_buffer.h** | 1.01 | utility | typesafe dynamic array for C (i.e. approximation to vector<>), doesn't compile as C++
-**stb_textedit.h** | 1.4 | UI | guts of a text editor for games etc implementing them from scratch
+**stb_textedit.h** | 1.5 | UI | guts of a text editor for games etc implementing them from scratch
 **stb_dxt.h** | 1.04 | 3D&nbsp;graphics | Fabian "ryg" Giesen's real-time DXT compressor
-**stb_herringbone_wang_tile.h** | 0.6 | games | herringbone Wang tile map generator
 **stb_perlin.h** | 0.2 | 3D&nbsp;graphics | revised Perlin noise (3D input, 1D output)
+**stb_herringbone_wang_tile.h** | 0.6 | games | herringbone Wang tile map generator
 **stb_c_lexer.h** | 0.06 | parsing | simplify writing parsers for C-like languages
 **stb_divide.h** | 0.91 | math | more useful 32-bit modulus e.g. "euclidean divide"
 **stb.h** | 2.23 | misc | helper functions for C, mostly redundant in C++; basically author's personal stuff

docs/stb_resample_ideas.txt

@@ -190,3 +190,12 @@ Cubic sampling function for seperable cubic:
    f(x) = 0                               otherwise
    "a" is configurable, try -1/2 (from http://pixinsight.com/forum/index.php?topic=556.0 )
 
+
+
+Wish list:
+   s0, t0, s1, t1 vs scale_x, scale_y, offset_x, offset_y - What's the best interface?
+   Separate wrap modes and filter modes per axis
+   Alpha test coverage respecting resize (FloatImage::alphaTestCoverage and FloatImage::scaleAlphaToCoverage: https://code.google.com/p/nvidia-texture-tools/source/browse/trunk/src/nvimage/FloatImage.cpp)
+   Installable filter kernels
+
+

stb_image.h

@@ -766,7 +766,7 @@ static void stbi__refill_buffer(stbi__context *s)
    int n = (s->io.read)(s->io_user_data,(char*)s->buffer_start,s->buflen);
    if (n == 0) {
       // at end of file, treat same as if from memory, but need to handle case
-      // where s->img_buffer isn't pointing to safe memory, stbi__err.g. 0-byte file
+      // where s->img_buffer isn't pointing to safe memory, e.g. 0-byte file
       s->read_from_callbacks = 0;
       s->img_buffer = s->buffer_start;
       s->img_buffer_end = s->buffer_start+1;
@@ -864,7 +864,7 @@ static stbi__uint32 stbi__get32le(stbi__context *s)
 //////////////////////////////////////////////////////////////////////////////
 //
 //  generic converter from built-in img_n to req_comp
-//    individual types do this automatically as much as possible (stbi__err.g. jpeg
+//    individual types do this automatically as much as possible (e.g. jpeg
 //    does all cases internally since it needs to colorspace convert anyway,
 //    and it never has alpha, so very few cases ). png can automatically
 //    interleave an alpha=255 channel, but falls back to this for other cases
@@ -1611,12 +1611,12 @@ static int stbi__process_frame_header(stbi__jpeg *z, int scan)
    z->img_mcu_y = (s->img_y + z->img_mcu_h-1) / z->img_mcu_h;
 
    for (i=0; i < s->img_n; ++i) {
-      // number of effective pixels (stbi__err.g. for non-interleaved MCU)
+      // number of effective pixels (e.g. for non-interleaved MCU)
       z->img_comp[i].x = (s->img_x * z->img_comp[i].h + h_max-1) / h_max;
       z->img_comp[i].y = (s->img_y * z->img_comp[i].v + v_max-1) / v_max;
       // to simplify generation, we'll allocate enough memory to decode
       // the bogus oversized data from using interleaved MCUs and their
-      // big blocks (stbi__err.g. a 16x16 iMCU on an image of width 33); we won't
+      // big blocks (e.g. a 16x16 iMCU on an image of width 33); we won't
       // discard the extra data until colorspace conversion
       z->img_comp[i].w2 = z->img_mcu_x * z->img_comp[i].h * 8;
       z->img_comp[i].h2 = z->img_mcu_y * z->img_comp[i].v * 8;
@@ -1636,7 +1636,7 @@ static int stbi__process_frame_header(stbi__jpeg *z, int scan)
    return 1;
 }
 
-// use comparisons since in some cases we handle more than one case (stbi__err.g. stbi__SOF)
+// use comparisons since in some cases we handle more than one case (e.g. stbi__SOF)
 #define stbi__DNL(x)         ((x) == 0xdc)
 #define stbi__SOI(x)         ((x) == 0xd8)
 #define stbi__EOI(x)         ((x) == 0xd9)
@@ -2025,7 +2025,7 @@ stbi_inline static int stbi__bit_reverse(int v, int bits)
 {
    STBI_ASSERT(bits <= 16);
    // to bit reverse n bits, reverse 16 and shift
-   // stbi__err.g. 11 bits, bit reverse and shift away 5
+   // e.g. 11 bits, bit reverse and shift away 5
    return stbi__bitreverse16(v) >> (16-bits);
 }
 

stb_image_resize.h

@@ -0,0 +1,2595 @@
+/* stb_image_resize - v0.90 - public domain image resizing
+   by Jorge L Rodriguez (@VinoBS) - 2014
+   http://github.com/nothings/stb
+
+   Written with emphasis on usability, portability, and efficiency. (No
+   SIMD or threads, so it be easily outperformed by libs that use those.)
+   Only scaling and translation is supported, no rotations or shears.
+   Easy API downsamples w/Mitchell filter, upsamples w/cubic interpolation.
+
+   COMPILING & LINKING
+      In one C/C++ file that #includes this file, do this:
+         #define STB_IMAGE_RESIZE_IMPLEMENTATION
+      before the #include. That will create the implementation in that file.
+
+   QUICKSTART
+      stbir_resize_uint8(      input_pixels , in_w , in_h , 0,
+                               output_pixels, out_w, out_h, 0, num_channels)
+      stbir_resize_float(...)
+      stbir_resize_uint8_srgb( input_pixels , in_w , in_h , 0,
+                               output_pixels, out_w, out_h, 0,
+                               num_channels , alpha_chan  , 0)
+      stbir_resize_uint8_srgb_edgemode(
+                               input_pixels , in_w , in_h , 0, 
+                               output_pixels, out_w, out_h, 0, 
+                               num_channels , alpha_chan  , 0, STBIR_EDGE_CLAMP)
+                                                            // WRAP/REFLECT/ZERO
+
+   FULL API
+      See the "header file" section of the source for API documentation.
+
+   ADDITIONAL DOCUMENTATION
+
+      SRGB & FLOATING POINT REPRESENTATION
+         Some srgb-related code in this library relies on floats being 32-bit
+         IEEE floating point, and relies on a specific bitpacking order of C
+         bitfields. If you are on a system that uses non-IEEE floats or packs
+         C bitfields in the opposite order, then you can use a slower fallback
+         codepath by defining STBIR_NON_IEEE_FLOAT. (We didn't make this choice
+         idly; using mostly-but-not-100%-portable-code for this is a massive
+         speedup, especially upsampling where colorspace conversion dominates.)
+
+      MEMORY ALLOCATION
+         The resize functions here perform a single memory allocation using
+         malloc. To control the memory allocation, before the #include that
+         triggers the implementation, do:
+
+            #define STBIR_MALLOC(size,context) ...
+            #define STBIR_FREE(ptr,context)   ...
+
+         Each resize function makes exactly one call to malloc/free, so to use
+         temp memory, store the temp memory in the context and return that.
+
+      ASSERT
+         Define STBIR_ASSERT(boolval) to override assert() and not use assert.h
+
+      OPTIMIZATION
+         Define STBIR_SATURATE_INT to compute clamp values in-range using
+         integer operations instead of float operations. This may be faster
+         on some platforms.
+
+      DEFAULT FILTERS
+         For functions which don't provide explicit control over what filters
+         to use, you can change the compile-time defaults with
+
+            #define STBIR_DEFAULT_FILTER_UPSAMPLE     STBIR_FILTER_something
+            #define STBIR_DEFAULT_FILTER_DOWNSAMPLE   STBIR_FILTER_something
+
+         See stbir_filter in the header-file section for the list of filters.
+
+      NEW FILTERS
+         A number of 1D filter kernels are used. For a list of
+         supported filters see the stbir_filter enum. To add a new filter,
+         write a filter function and add it to stbir__filter_info_table.
+
+      PROGRESS
+         For interactive use with slow resize operations, you can install
+         a progress-report callback:
+
+            #define STBIR_PROGRESS_REPORT(val)   some_func(val)
+
+         The parameter val is a float which goes from 0 to 1 as progress is made.
+
+         For example:
+
+            static void my_progress_report(float progress);
+            #define STBIR_PROGRESS_REPORT(val) my_progress_report(val)
+
+            #define STB_IMAGE_RESIZE_IMPLEMENTATION
+            #include "stb_image_resize.h"
+
+            static void my_progress_report(float progress)
+            {
+               printf("Progress: %f%%\n", progress*100);
+            }
+
+      MAX CHANNELS
+         If your image has more than 64 channels, define STBIR_MAX_CHANNELS
+         to the max you'll have.
+
+      ALPHA CHANNEL
+         Most of the resizing functions provide the ability to control how
+         the alpha channel of an image is processed. The important things
+         to know about this:
+
+         1. The best mathematically-behaved version of alpha to use is
+         called "premultiplied alpha", in which the other color channels
+         have had the alpha value multiplied in. If you use premultiplied
+         alpha, linear filtering (such as image resampling done by this
+         library, or performed in texture units on GPUs) does the "right
+         thing". While premultiplied alpha is standard in the movie CGI
+         industry, it is still uncommon in the videogame/real-time world.
+
+         If you linearly filter non-premultiplied alpha, strange effects
+         occur. (For example, the average of 1% opaque bright green
+         and 99% opaque black produces 50% transparent dark green when
+         non-premultiplied, whereas premultiplied it produces 50%
+         transparent near-black. The former introduces green energy
+         that doesn't exist in the source image.)
+
+         2. Artists should not edit premultiplied-alpha images; artists
+         want non-premultiplied alpha images. Thus, art tools generally output
+         non-premultiplied alpha images.
+
+         3. You will get best results in most cases by converting images
+         to premultiplied alpha before processing them mathematically.
+
+         4. If you pass the flag STBIR_FLAG_ALPHA_PREMULTIPLIED, the
+         resizer does not do anything special for the alpha channel;
+         it is resampled identically to other channels. This produces
+         the correct results for premultiplied-alpha images, but produces
+         less-than-ideal results for non-premultiplied-alpha images.
+
+         5. If you do not pass the flag STBIR_FLAG_ALPHA_PREMULTIPLIED,
+         then the resizer weights the contribution of input pixels
+         based on their alpha values, or, equivalently, it multiplies
+         the alpha value into the color channels, resamples, then divides
+         by the resultant alpha value. Input pixels which have alpha=0 do
+         not contribute at all to output pixels unless _all_ of the input
+         pixels affecting that output pixel have alpha=0, in which case
+         the result for that pixel is the same as it would be without
+         STBIR_FLAG_ALPHA_PREMULTIPLIED. However, this is only true for
+         input images in integer formats. For input images in float format,
+         input pixels with alpha=0 have no effect, and output pixels
+         which have alpha=0 will be 0 in all channels. (For float images,
+         you can manually achieve the same result by adding a tiny epsilon
+         value to the alpha channel of every image, and then subtracting
+         or clamping it at the end.)
+
+         6. You can suppress the behavior described in #5 and make
+         all-0-alpha pixels have 0 in all channels by #defining
+         STBIR_NO_ALPHA_EPSILON.
+
+         7. You can separately control whether the alpha channel is
+         interpreted as linear or affected by the colorspace. By default
+         it is linear; you almost never want to apply the colorspace.
+         (For example, graphics hardware does not apply sRGB conversion
+         to the alpha channel.)
+
+   ADDITIONAL CONTRIBUTORS
+      Sean Barrett: API design, optimizations
+         
+   REVISIONS
+      0.90 (2014-09-17) first released version
+
+   LICENSE
+      This software is in the public domain. Where that dedication is not
+      recognized, you are granted a perpetual, irrevocable license to copy
+      and modify this file as you see fit.
+
+   TODO
+      Don't decode all of the image data when only processing a partial tile
+      Don't use full-width decode buffers when only processing a partial tile
+      When processing wide images, break processing into tiles so data fits in L1 cache
+      Installable filters?
+      Resize that respects alpha test coverage
+         (Reference code: FloatImage::alphaTestCoverage and FloatImage::scaleAlphaToCoverage:
+         https://code.google.com/p/nvidia-texture-tools/source/browse/trunk/src/nvimage/FloatImage.cpp )
+*/
+
+#ifndef STBIR_INCLUDE_STB_IMAGE_RESIZE_H
+#define STBIR_INCLUDE_STB_IMAGE_RESIZE_H
+
+#ifdef _MSC_VER
+typedef unsigned char  stbir_uint8;
+typedef unsigned short stbir_uint16;
+typedef unsigned int   stbir_uint32;
+#else
+#include <stdint.h>
+typedef uint8_t  stbir_uint8;
+typedef uint16_t stbir_uint16;
+typedef uint32_t stbir_uint32;
+#endif
+
+#ifdef STB_IMAGE_RESIZE_STATIC
+#define STBIRDEF static
+#else
+#ifdef __cplusplus
+#define STBIRDEF extern "C"
+#else
+#define STBIRDEF extern
+#endif
+#endif
+
+
+//////////////////////////////////////////////////////////////////////////////
+//
+// Easy-to-use API:
+//
+//     * "input pixels" points to an array of image data with 'num_channels' channels (e.g. RGB=3, RGBA=4)
+//     * input_w is input image width (x-axis), input_h is input image height (y-axis)
+//     * stride is the offset between successive rows of image data in memory, in bytes. you can
+//       specify 0 to mean packed continuously in memory
+//     * alpha channel is treated identically to other channels.
+//     * colorspace is linear or sRGB as specified by function name
+//     * returned result is 1 for success or 0 in case of an error.
+//       #define STBIR_ASSERT() to trigger an assert on parameter validation errors.
+//     * Memory required grows approximately linearly with input and output size, but with
+//       discontinuities at input_w == output_w and input_h == output_h.
+//     * These functions use a "default" resampling filter defined at compile time. To change the filter,
+//       you can change the compile-time defaults by #defining STBIR_DEFAULT_FILTER_UPSAMPLE
+//       and STBIR_DEFAULT_FILTER_DOWNSAMPLE, or you can use the medium-complexity API.
+
+STBIRDEF int stbir_resize_uint8(     const unsigned char *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                           unsigned char *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                     int num_channels);
+
+STBIRDEF int stbir_resize_float(     const float *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                           float *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                     int num_channels);
+
+
+// The following functions interpret image data as gamma-corrected sRGB. 
+// Specify STBIR_ALPHA_CHANNEL_NONE if you have no alpha channel,
+// or otherwise provide the index of the alpha channel. Flags value
+// of 0 will probably do the right thing if you're not sure what
+// the flags mean.
+
+#define STBIR_ALPHA_CHANNEL_NONE       -1
+
+// Set this flag if your texture has premultiplied alpha. Otherwise, stbir will
+// use alpha-weighted resampling (effectively premultiplying, resampling,
+// then unpremultiplying).
+#define STBIR_FLAG_ALPHA_PREMULTIPLIED    (1 << 0)
+// The specified alpha channel should be handled as gamma-corrected value even
+// when doing sRGB operations.
+#define STBIR_FLAG_ALPHA_USES_COLORSPACE  (1 << 1)
+
+STBIRDEF int stbir_resize_uint8_srgb(const unsigned char *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                           unsigned char *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                     int num_channels, int alpha_channel, int flags);
+
+
+typedef enum
+{
+    STBIR_EDGE_CLAMP   = 1,
+    STBIR_EDGE_REFLECT = 2,
+    STBIR_EDGE_WRAP    = 3,
+    STBIR_EDGE_ZERO    = 4,
+} stbir_edge;
+
+// This function adds the ability to specify how requests to sample off the edge of the image are handled.
+STBIRDEF int stbir_resize_uint8_srgb_edgemode(const unsigned char *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                                    unsigned char *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                              int num_channels, int alpha_channel, int flags,
+                                              stbir_edge edge_wrap_mode);
+
+//////////////////////////////////////////////////////////////////////////////
+//
+// Medium-complexity API
+//
+// This extends the easy-to-use API as follows:
+//
+//     * Alpha-channel can be processed separately
+//       * If alpha_channel is not STBIR_ALPHA_CHANNEL_NONE
+//         * Alpha channel will not be gamma corrected (unless flags&STBIR_FLAG_GAMMA_CORRECT)
+//         * Filters will be weighted by alpha channel (unless flags&STBIR_FLAG_ALPHA_PREMULTIPLIED)
+//     * Filter can be selected explicitly
+//     * uint16 image type
+//     * sRGB colorspace available for all types
+//     * context parameter for passing to STBIR_MALLOC
+
+typedef enum
+{
+    STBIR_FILTER_DEFAULT      = 0,  // use same filter type that easy-to-use API chooses
+    STBIR_FILTER_BOX          = 1,  // A trapezoid w/1-pixel wide ramps, same result as box for integer scale ratios
+    STBIR_FILTER_TRIANGLE     = 2,  // On upsampling, produces same results as bilinear texture filtering
+    STBIR_FILTER_CUBICBSPLINE = 3,  // The cubic b-spline (aka Mitchell-Netrevalli with B=1,C=0), gaussian-esque
+    STBIR_FILTER_CATMULLROM   = 4,  // An interpolating cubic spline
+    STBIR_FILTER_MITCHELL     = 5,  // Mitchell-Netrevalli filter with B=1/3, C=1/3
+} stbir_filter;
+
+typedef enum
+{
+    STBIR_COLORSPACE_LINEAR,
+    STBIR_COLORSPACE_SRGB,
+
+    STBIR_MAX_COLORSPACES,
+} stbir_colorspace;
+
+// The following functions are all identical except for the type of the image data
+
+STBIRDEF int stbir_resize_uint8_generic( const unsigned char *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                               unsigned char *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                         int num_channels, int alpha_channel, int flags,
+                                         stbir_edge edge_wrap_mode, stbir_filter filter, stbir_colorspace space, 
+                                         void *alloc_context);
+
+STBIRDEF int stbir_resize_uint16_generic(const stbir_uint16 *input_pixels  , int input_w , int input_h , int input_stride_in_bytes,
+                                               stbir_uint16 *output_pixels , int output_w, int output_h, int output_stride_in_bytes,
+                                         int num_channels, int alpha_channel, int flags,
+                                         stbir_edge edge_wrap_mode, stbir_filter filter, stbir_colorspace space, 
+                                         void *alloc_context);
+
+STBIRDEF int stbir_resize_float_generic( const float *input_pixels         , int input_w , int input_h , int input_stride_in_bytes,
+                                               float *output_pixels        , int output_w, int output_h, int output_stride_in_bytes,
+                                         int num_channels, int alpha_channel, int flags,
+                                         stbir_edge edge_wrap_mode, stbir_filter filter, stbir_colorspace space, 
+                                         void *alloc_context);
+
+
+
+//////////////////////////////////////////////////////////////////////////////
+//
+// Full-complexity API
+//
+// This extends the medium API as follows:
+//
+//       * uint32 image type
+//     * not typesafe
+//     * separate filter types for each axis
+//     * separate edge modes for each axis
+//     * can specify scale explicitly for subpixel correctness
+//     * can specify image source tile using texture coordinates
+
+typedef enum
+{
+    STBIR_TYPE_UINT8 ,
+    STBIR_TYPE_UINT16,
+    STBIR_TYPE_UINT32,
+    STBIR_TYPE_FLOAT ,
+
+    STBIR_MAX_TYPES
+} stbir_datatype;
+
+STBIRDEF int stbir_resize(         const void *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                         void *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                   stbir_datatype datatype,
+                                   int num_channels, int alpha_channel, int flags,
+                                   stbir_edge edge_mode_horizontal, stbir_edge edge_mode_vertical, 
+                                   stbir_filter filter_horizontal,  stbir_filter filter_vertical,
+                                   stbir_colorspace space, void *alloc_context);
+
+STBIRDEF int stbir_resize_subpixel(const void *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                         void *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                   stbir_datatype datatype,
+                                   int num_channels, int alpha_channel, int flags,
+                                   stbir_edge edge_mode_horizontal, stbir_edge edge_mode_vertical, 
+                                   stbir_filter filter_horizontal,  stbir_filter filter_vertical,
+                                   stbir_colorspace space, void *alloc_context,
+                                   float x_scale, float y_scale,
+                                   float x_offset, float y_offset);
+
+STBIRDEF int stbir_resize_region(  const void *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                         void *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                   stbir_datatype datatype,
+                                   int num_channels, int alpha_channel, int flags,
+                                   stbir_edge edge_mode_horizontal, stbir_edge edge_mode_vertical, 
+                                   stbir_filter filter_horizontal,  stbir_filter filter_vertical,
+                                   stbir_colorspace space, void *alloc_context,
+                                   float s0, float t0, float s1, float t1);
+// (s0, t0) & (s1, t1) are the top-left and bottom right corner (uv addressing style: [0, 1]x[0, 1]) of a region of the input image to use.
+
+//
+//
+////   end header file   /////////////////////////////////////////////////////
+#endif // STBIR_INCLUDE_STB_IMAGE_RESIZE_H
+
+
+
+
+
+#ifdef STB_IMAGE_RESIZE_IMPLEMENTATION
+
+#ifndef STBIR_ASSERT
+#include <assert.h>
+#define STBIR_ASSERT(x) assert(x)
+#endif
+
+#ifdef STBIR_DEBUG
+#define STBIR__DEBUG_ASSERT STBIR_ASSERT
+#else
+#define STBIR__DEBUG_ASSERT
+#endif
+
+// If you hit this it means I haven't done it yet.
+#define STBIR__UNIMPLEMENTED(x) STBIR_ASSERT(!(x))
+
+// For memset
+#include <string.h>
+
+#include <math.h>
+
+#ifndef STBIR_MALLOC
+#include <stdlib.h>
+#define STBIR_MALLOC(size,c) malloc(size)
+#define STBIR_FREE(ptr,c)    free(ptr)
+#endif
+
+#ifndef _MSC_VER
+#ifdef __cplusplus
+#define stbir__inline inline
+#else
+#define stbir__inline
+#endif
+#else
+#define stbir__inline __forceinline
+#endif
+
+
+// should produce compiler error if size is wrong
+typedef unsigned char stbir__validate_uint32[sizeof(stbir_uint32) == 4 ? 1 : -1];
+
+#ifdef _MSC_VER
+#define STBIR__NOTUSED(v)  (void)(v)
+#else
+#define STBIR__NOTUSED(v)  (void)sizeof(v)
+#endif
+
+#define STBIR__ARRAY_SIZE(a) (sizeof((a))/sizeof((a)[0]))
+
+#ifndef STBIR_DEFAULT_FILTER_UPSAMPLE
+#define STBIR_DEFAULT_FILTER_UPSAMPLE    STBIR_FILTER_CATMULLROM
+#endif
+
+#ifndef STBIR_DEFAULT_FILTER_DOWNSAMPLE
+#define STBIR_DEFAULT_FILTER_DOWNSAMPLE  STBIR_FILTER_MITCHELL
+#endif
+
+#ifndef STBIR_PROGRESS_REPORT
+#define STBIR_PROGRESS_REPORT(float_0_to_1)
+#endif
+
+#ifndef STBIR_MAX_CHANNELS
+#define STBIR_MAX_CHANNELS 64
+#endif
+
+#if STBIR_MAX_CHANNELS > 65536
+#error "Too many channels; STBIR_MAX_CHANNELS must be no more than 65536."
+// because we store the indices in 16-bit variables
+#endif
+
+// This value is added to alpha just before premultiplication to avoid
+// zeroing out color values. It is equivalent to 2^-80. If you don't want
+// that behavior (it may interfere if you have floating point images with
+// very small alpha values) then you can define STBIR_NO_ALPHA_EPSILON to
+// disable it.
+#ifndef STBIR_ALPHA_EPSILON
+#define STBIR_ALPHA_EPSILON ((float)1 / (1 << 20) / (1 << 20) / (1 << 20) / (1 << 20))
+#endif
+
+
+
+#ifdef _MSC_VER
+#define STBIR__UNUSED_PARAM(v)  (void)(v)
+#else
+#define STBIR__UNUSED_PARAM(v)  (void)sizeof(v)
+#endif
+
+// must match stbir_datatype
+static unsigned char stbir__type_size[] = {
+    1, // STBIR_TYPE_UINT8
+    2, // STBIR_TYPE_UINT16
+    4, // STBIR_TYPE_UINT32
+    4, // STBIR_TYPE_FLOAT
+};
+
+// Kernel function centered at 0
+typedef float (stbir__kernel_fn)(float x, float scale);
+typedef float (stbir__support_fn)(float scale);
+
+typedef struct
+{
+    stbir__kernel_fn* kernel;
+    stbir__support_fn* support;
+} stbir__filter_info;
+
+// When upsampling, the contributors are which source pixels contribute.
+// When downsampling, the contributors are which destination pixels are contributed to.
+typedef struct
+{
+    int n0; // First contributing pixel
+    int n1; // Last contributing pixel
+} stbir__contributors;
+
+typedef struct
+{
+    const void* input_data;
+    int input_w;
+    int input_h;
+    int input_stride_bytes;
+
+    void* output_data;
+    int output_w;
+    int output_h;
+    int output_stride_bytes;
+
+    float s0, t0, s1, t1;
+
+    float horizontal_shift; // Units: output pixels
+    float vertical_shift;   // Units: output pixels
+    float horizontal_scale;
+    float vertical_scale;
+
+    int channels;
+    int alpha_channel;
+    stbir_uint32 flags;
+    stbir_datatype type;
+    stbir_filter horizontal_filter;
+    stbir_filter vertical_filter;
+    stbir_edge edge_horizontal;
+    stbir_edge edge_vertical;
+    stbir_colorspace colorspace;
+
+    stbir__contributors* horizontal_contributors;
+    float* horizontal_coefficients;
+
+    stbir__contributors* vertical_contributors;
+    float* vertical_coefficients;
+
+    int decode_buffer_pixels;
+    float* decode_buffer;
+
+    float* horizontal_buffer;
+
+    // cache these because ceil/floor are inexplicably showing up in profile
+    int horizontal_coefficient_width;
+    int vertical_coefficient_width;
+    int horizontal_filter_pixel_width;
+    int vertical_filter_pixel_width;
+    int horizontal_filter_pixel_margin;
+    int vertical_filter_pixel_margin;
+    int horizontal_num_contributors;
+    int vertical_num_contributors;
+
+    int ring_buffer_length_bytes; // The length of an individual entry in the ring buffer. The total number of ring buffers is stbir__get_filter_pixel_width(filter)
+    int ring_buffer_first_scanline;
+    int ring_buffer_last_scanline;
+    int ring_buffer_begin_index;
+    float* ring_buffer;
+
+    float* encode_buffer; // A temporary buffer to store floats so we don't lose precision while we do multiply-adds.
+
+    int horizontal_contributors_size;
+    int horizontal_coefficients_size;
+    int vertical_contributors_size;
+    int vertical_coefficients_size;
+    int decode_buffer_size;
+    int horizontal_buffer_size;
+    int ring_buffer_size;
+    int encode_buffer_size;
+} stbir__info;
+
+static stbir__inline int stbir__min(int a, int b)
+{
+    return a < b ? a : b;
+}
+
+static stbir__inline int stbir__max(int a, int b)
+{
+    return a > b ? a : b;
+}
+
+static stbir__inline float stbir__saturate(float x)
+{
+    if (x < 0)
+        return 0;
+
+    if (x > 1)
+        return 1;
+
+    return x;
+}
+
+#ifdef STBIR_SATURATE_INT
+static stbir__inline stbir_uint8 stbir__saturate8(int x)
+{
+    if ((unsigned int) x <= 255)
+        return x;
+
+    if (x < 0)
+        return 0;
+
+    return 255;
+}
+
+static stbir__inline stbir_uint16 stbir__saturate16(int x)
+{
+    if ((unsigned int) x <= 65535)
+        return x;
+
+    if (x < 0)
+        return 0;
+
+    return 65535;
+}
+#endif
+
+static float stbir__srgb_uchar_to_linear_float[256] = {
+    0.000000f, 0.000304f, 0.000607f, 0.000911f, 0.001214f, 0.001518f, 0.001821f, 0.002125f, 0.002428f, 0.002732f, 0.003035f,
+    0.003347f, 0.003677f, 0.004025f, 0.004391f, 0.004777f, 0.005182f, 0.005605f, 0.006049f, 0.006512f, 0.006995f, 0.007499f,
+    0.008023f, 0.008568f, 0.009134f, 0.009721f, 0.010330f, 0.010960f, 0.011612f, 0.012286f, 0.012983f, 0.013702f, 0.014444f,
+    0.015209f, 0.015996f, 0.016807f, 0.017642f, 0.018500f, 0.019382f, 0.020289f, 0.021219f, 0.022174f, 0.023153f, 0.024158f,
+    0.025187f, 0.026241f, 0.027321f, 0.028426f, 0.029557f, 0.030713f, 0.031896f, 0.033105f, 0.034340f, 0.035601f, 0.036889f,
+    0.038204f, 0.039546f, 0.040915f, 0.042311f, 0.043735f, 0.045186f, 0.046665f, 0.048172f, 0.049707f, 0.051269f, 0.052861f,
+    0.054480f, 0.056128f, 0.057805f, 0.059511f, 0.061246f, 0.063010f, 0.064803f, 0.066626f, 0.068478f, 0.070360f, 0.072272f,
+    0.074214f, 0.076185f, 0.078187f, 0.080220f, 0.082283f, 0.084376f, 0.086500f, 0.088656f, 0.090842f, 0.093059f, 0.095307f,
+    0.097587f, 0.099899f, 0.102242f, 0.104616f, 0.107023f, 0.109462f, 0.111932f, 0.114435f, 0.116971f, 0.119538f, 0.122139f,
+    0.124772f, 0.127438f, 0.130136f, 0.132868f, 0.135633f, 0.138432f, 0.141263f, 0.144128f, 0.147027f, 0.149960f, 0.152926f,
+    0.155926f, 0.158961f, 0.162029f, 0.165132f, 0.168269f, 0.171441f, 0.174647f, 0.177888f, 0.181164f, 0.184475f, 0.187821f,
+    0.191202f, 0.194618f, 0.198069f, 0.201556f, 0.205079f, 0.208637f, 0.212231f, 0.215861f, 0.219526f, 0.223228f, 0.226966f,
+    0.230740f, 0.234551f, 0.238398f, 0.242281f, 0.246201f, 0.250158f, 0.254152f, 0.258183f, 0.262251f, 0.266356f, 0.270498f,
+    0.274677f, 0.278894f, 0.283149f, 0.287441f, 0.291771f, 0.296138f, 0.300544f, 0.304987f, 0.309469f, 0.313989f, 0.318547f,
+    0.323143f, 0.327778f, 0.332452f, 0.337164f, 0.341914f, 0.346704f, 0.351533f, 0.356400f, 0.361307f, 0.366253f, 0.371238f,
+    0.376262f, 0.381326f, 0.386430f, 0.391573f, 0.396755f, 0.401978f, 0.407240f, 0.412543f, 0.417885f, 0.423268f, 0.428691f,
+    0.434154f, 0.439657f, 0.445201f, 0.450786f, 0.456411f, 0.462077f, 0.467784f, 0.473532f, 0.479320f, 0.485150f, 0.491021f,
+    0.496933f, 0.502887f, 0.508881f, 0.514918f, 0.520996f, 0.527115f, 0.533276f, 0.539480f, 0.545725f, 0.552011f, 0.558340f,
+    0.564712f, 0.571125f, 0.577581f, 0.584078f, 0.590619f, 0.597202f, 0.603827f, 0.610496f, 0.617207f, 0.623960f, 0.630757f,
+    0.637597f, 0.644480f, 0.651406f, 0.658375f, 0.665387f, 0.672443f, 0.679543f, 0.686685f, 0.693872f, 0.701102f, 0.708376f,
+    0.715694f, 0.723055f, 0.730461f, 0.737911f, 0.745404f, 0.752942f, 0.760525f, 0.768151f, 0.775822f, 0.783538f, 0.791298f,
+    0.799103f, 0.806952f, 0.814847f, 0.822786f, 0.830770f, 0.838799f, 0.846873f, 0.854993f, 0.863157f, 0.871367f, 0.879622f,
+    0.887923f, 0.896269f, 0.904661f, 0.913099f, 0.921582f, 0.930111f, 0.938686f, 0.947307f, 0.955974f, 0.964686f, 0.973445f,
+    0.982251f, 0.991102f, 1.0f
+};
+
+static float stbir__srgb_to_linear(float f)
+{
+    if (f <= 0.04045f)
+        return f / 12.92f;
+    else
+        return (float)pow((f + 0.055f) / 1.055f, 2.4f);
+}
+
+static float stbir__linear_to_srgb(float f)
+{
+    if (f <= 0.0031308f)
+        return f * 12.92f;
+    else
+        return 1.055f * (float)pow(f, 1 / 2.4f) - 0.055f;
+}
+
+#ifndef STBIR_NON_IEEE_FLOAT
+// From https://gist.github.com/rygorous/2203834
+
+typedef union
+{
+    stbir_uint32 u;
+    float f;
+    struct
+    {
+        stbir_uint32 Mantissa : 23;
+        stbir_uint32 Exponent : 8;
+        stbir_uint32 Sign : 1;
+    };
+} stbir__FP32;
+
+static const stbir_uint32 fp32_to_srgb8_tab4[104] = {
+    0x0073000d, 0x007a000d, 0x0080000d, 0x0087000d, 0x008d000d, 0x0094000d, 0x009a000d, 0x00a1000d,
+    0x00a7001a, 0x00b4001a, 0x00c1001a, 0x00ce001a, 0x00da001a, 0x00e7001a, 0x00f4001a, 0x0101001a,
+    0x010e0033, 0x01280033, 0x01410033, 0x015b0033, 0x01750033, 0x018f0033, 0x01a80033, 0x01c20033,
+    0x01dc0067, 0x020f0067, 0x02430067, 0x02760067, 0x02aa0067, 0x02dd0067, 0x03110067, 0x03440067,
+    0x037800ce, 0x03df00ce, 0x044600ce, 0x04ad00ce, 0x051400ce, 0x057b00c5, 0x05dd00bc, 0x063b00b5,
+    0x06970158, 0x07420142, 0x07e30130, 0x087b0120, 0x090b0112, 0x09940106, 0x0a1700fc, 0x0a9500f2,
+    0x0b0f01cb, 0x0bf401ae, 0x0ccb0195, 0x0d950180, 0x0e56016e, 0x0f0d015e, 0x0fbc0150, 0x10630143,
+    0x11070264, 0x1238023e, 0x1357021d, 0x14660201, 0x156601e9, 0x165a01d3, 0x174401c0, 0x182401af,
+    0x18fe0331, 0x1a9602fe, 0x1c1502d2, 0x1d7e02ad, 0x1ed4028d, 0x201a0270, 0x21520256, 0x227d0240,
+    0x239f0443, 0x25c003fe, 0x27bf03c4, 0x29a10392, 0x2b6a0367, 0x2d1d0341, 0x2ebe031f, 0x304d0300,
+    0x31d105b0, 0x34a80555, 0x37520507, 0x39d504c5, 0x3c37048b, 0x3e7c0458, 0x40a8042a, 0x42bd0401,
+    0x44c20798, 0x488e071e, 0x4c1c06b6, 0x4f76065d, 0x52a50610, 0x55ac05cc, 0x5892058f, 0x5b590559,
+    0x5e0c0a23, 0x631c0980, 0x67db08f6, 0x6c55087f, 0x70940818, 0x74a007bd, 0x787d076c, 0x7c330723,
+};
+ 
+static stbir_uint8 stbir__linear_to_srgb_uchar(float in)
+{
+    static const stbir__FP32 almostone = { 0x3f7fffff }; // 1-eps
+    static const stbir__FP32 minval = { (127-13) << 23 };
+    stbir_uint32 tab,bias,scale,t;
+    stbir__FP32 f;
+ 
+    // Clamp to [2^(-13), 1-eps]; these two values map to 0 and 1, respectively.
+    // The tests are carefully written so that NaNs map to 0, same as in the reference
+    // implementation.
+    if (!(in > minval.f)) // written this way to catch NaNs
+        in = minval.f;
+    if (in > almostone.f)
+        in = almostone.f;
+ 
+    // Do the table lookup and unpack bias, scale
+    f.f = in;
+    tab = fp32_to_srgb8_tab4[(f.u - minval.u) >> 20];
+    bias = (tab >> 16) << 9;
+    scale = tab & 0xffff;
+ 
+    // Grab next-highest mantissa bits and perform linear interpolation
+    t = (f.u >> 12) & 0xff;
+    return (unsigned char) ((bias + scale*t) >> 16);
+}
+
+#else
+// sRGB transition values, scaled by 1<<28
+static int stbir__srgb_offset_to_linear_scaled[256] =
+{
+            0,     40738,    122216,    203693,    285170,    366648,    448125,    529603,
+       611080,    692557,    774035,    855852,    942009,   1033024,   1128971,   1229926,
+      1335959,   1447142,   1563542,   1685229,   1812268,   1944725,   2082664,   2226148,
+      2375238,   2529996,   2690481,   2856753,   3028870,   3206888,   3390865,   3580856,
+      3776916,   3979100,   4187460,   4402049,   4622919,   4850123,   5083710,   5323731,
+      5570236,   5823273,   6082892,   6349140,   6622065,   6901714,   7188133,   7481369,
+      7781466,   8088471,   8402427,   8723380,   9051372,   9386448,   9728650,  10078021,
+     10434603,  10798439,  11169569,  11548036,  11933879,  12327139,  12727857,  13136073,
+     13551826,  13975156,  14406100,  14844697,  15290987,  15745007,  16206795,  16676389,
+     17153826,  17639142,  18132374,  18633560,  19142734,  19659934,  20185196,  20718552,
+     21260042,  21809696,  22367554,  22933648,  23508010,  24090680,  24681686,  25281066,
+     25888850,  26505076,  27129772,  27762974,  28404716,  29055026,  29713942,  30381490,
+     31057708,  31742624,  32436272,  33138682,  33849884,  34569912,  35298800,  36036568,
+     36783260,  37538896,  38303512,  39077136,  39859796,  40651528,  41452360,  42262316,
+     43081432,  43909732,  44747252,  45594016,  46450052,  47315392,  48190064,  49074096,
+     49967516,  50870356,  51782636,  52704392,  53635648,  54576432,  55526772,  56486700,
+     57456236,  58435408,  59424248,  60422780,  61431036,  62449032,  63476804,  64514376,
+     65561776,  66619028,  67686160,  68763192,  69850160,  70947088,  72053992,  73170912,
+     74297864,  75434880,  76581976,  77739184,  78906536,  80084040,  81271736,  82469648,
+     83677792,  84896192,  86124888,  87363888,  88613232,  89872928,  91143016,  92423512,
+     93714432,  95015816,  96327688,  97650056,  98982952, 100326408, 101680440, 103045072,
+    104420320, 105806224, 107202800, 108610064, 110028048, 111456776, 112896264, 114346544,
+    115807632, 117279552, 118762328, 120255976, 121760536, 123276016, 124802440, 126339832,
+    127888216, 129447616, 131018048, 132599544, 134192112, 135795792, 137410592, 139036528,
+    140673648, 142321952, 143981456, 145652208, 147334208, 149027488, 150732064, 152447968,
+    154175200, 155913792, 157663776, 159425168, 161197984, 162982240, 164777968, 166585184,
+    168403904, 170234160, 172075968, 173929344, 175794320, 177670896, 179559120, 181458992,
+    183370528, 185293776, 187228736, 189175424, 191133888, 193104112, 195086128, 197079968,
+    199085648, 201103184, 203132592, 205173888, 207227120, 209292272, 211369392, 213458480,
+    215559568, 217672656, 219797792, 221934976, 224084240, 226245600, 228419056, 230604656,
+    232802400, 235012320, 237234432, 239468736, 241715280, 243974080, 246245120, 248528464,
+    250824112, 253132064, 255452368, 257785040, 260130080, 262487520, 264857376, 267239664,
+};
+
+static stbir_uint8 stbir__linear_to_srgb_uchar(float f)
+{
+    int x = (int) (f * (1 << 28)); // has headroom so you don't need to clamp
+    int v = 0;
+    int i;
+
+    // Refine the guess with a short binary search.
+    i = v + 128; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
+    i = v +  64; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
+    i = v +  32; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
+    i = v +  16; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
+    i = v +   8; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
+    i = v +   4; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
+    i = v +   2; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
+    i = v +   1; if (x >= stbir__srgb_offset_to_linear_scaled[i]) v = i;
+
+    return (stbir_uint8) v;
+}
+#endif
+
+static float stbir__filter_trapezoid(float x, float scale)
+{
+    float halfscale = scale / 2;
+    float t = 0.5f + halfscale;
+    STBIR__DEBUG_ASSERT(scale <= 1);
+
+    x = (float)fabs(x);
+
+    if (x >= t)
+        return 0;
+    else
+    {
+        float r = 0.5f - halfscale;
+        if (x <= r)
+            return 1;
+        else
+            return (t - x) / scale;
+    }
+}
+
+static float stbir__support_trapezoid(float scale)
+{
+    STBIR__DEBUG_ASSERT(scale <= 1);
+    return 0.5f + scale / 2;
+}
+
+static float stbir__filter_triangle(float x, float s)
+{
+    STBIR__UNUSED_PARAM(s);
+
+    x = (float)fabs(x);
+
+    if (x <= 1.0f)
+        return 1 - x;
+    else
+        return 0;
+}
+
+static float stbir__filter_cubic(float x, float s)
+{
+    STBIR__UNUSED_PARAM(s);
+
+    x = (float)fabs(x);
+
+    if (x < 1.0f)
+        return (4 + x*x*(3*x - 6))/6;
+    else if (x < 2.0f)
+        return (8 + x*(-12 + x*(6 - x)))/6;
+
+    return (0.0f);
+}
+
+static float stbir__filter_catmullrom(float x, float s)
+{
+    STBIR__UNUSED_PARAM(s);
+
+    x = (float)fabs(x);
+
+    if (x < 1.0f)
+        return 1 - x*x*(2.5f - 1.5f*x);
+    else if (x < 2.0f)
+        return 2 - x*(4 + x*(0.5f*x - 2.5f));
+
+    return (0.0f);
+}
+
+static float stbir__filter_mitchell(float x, float s)
+{
+    STBIR__UNUSED_PARAM(s);
+
+    x = (float)fabs(x);
+
+    if (x < 1.0f)
+        return (16 + x*x*(21 * x - 36))/18;
+    else if (x < 2.0f)
+        return (32 + x*(-60 + x*(36 - 7*x)))/18;
+
+    return (0.0f);
+}
+
+static float stbir__support_zero(float s)
+{
+    STBIR__UNUSED_PARAM(s);
+    return 0;
+}
+
+static float stbir__support_one(float s)
+{
+    STBIR__UNUSED_PARAM(s);
+    return 1;
+}
+
+static float stbir__support_two(float s)
+{
+    STBIR__UNUSED_PARAM(s);
+    return 2;
+}
+
+static stbir__filter_info stbir__filter_info_table[] = {
+        { NULL,                     stbir__support_zero },
+        { stbir__filter_trapezoid,  stbir__support_trapezoid },
+        { stbir__filter_triangle,   stbir__support_one },
+        { stbir__filter_cubic,      stbir__support_two },
+        { stbir__filter_catmullrom, stbir__support_two },
+        { stbir__filter_mitchell,   stbir__support_two },
+};
+
+stbir__inline static int stbir__use_upsampling(float ratio)
+{
+    return ratio > 1;
+}
+
+stbir__inline static int stbir__use_width_upsampling(stbir__info* stbir_info)
+{
+    return stbir__use_upsampling(stbir_info->horizontal_scale);
+}
+
+stbir__inline static int stbir__use_height_upsampling(stbir__info* stbir_info)
+{
+    return stbir__use_upsampling(stbir_info->vertical_scale);
+}
+
+// This is the maximum number of input samples that can affect an output sample
+// with the given filter
+static int stbir__get_filter_pixel_width(stbir_filter filter, float scale)
+{
+    STBIR_ASSERT(filter != 0);
+    STBIR_ASSERT(filter < STBIR__ARRAY_SIZE(stbir__filter_info_table));
+
+    if (stbir__use_upsampling(scale))
+        return (int)ceil(stbir__filter_info_table[filter].support(1/scale) * 2);
+    else
+        return (int)ceil(stbir__filter_info_table[filter].support(scale) * 2 / scale);
+}
+
+// This is how much to expand buffers to account for filters seeking outside
+// the image boundaries.
+static int stbir__get_filter_pixel_margin(stbir_filter filter, float scale)
+{
+    return stbir__get_filter_pixel_width(filter, scale) / 2;
+}
+
+static int stbir__get_coefficient_width(stbir_filter filter, float scale)
+{
+    if (stbir__use_upsampling(scale))
+        return (int)ceil(stbir__filter_info_table[filter].support(1 / scale) * 2);
+    else
+        return (int)ceil(stbir__filter_info_table[filter].support(scale) * 2);
+}
+
+static int stbir__get_contributors(float scale, stbir_filter filter, int input_size, int output_size)
+{
+    if (stbir__use_upsampling(scale))
+        return output_size;
+    else
+        return (input_size + stbir__get_filter_pixel_margin(filter, scale) * 2);
+}
+
+static int stbir__get_total_horizontal_coefficients(stbir__info* info)
+{
+    return info->horizontal_num_contributors
+         * stbir__get_coefficient_width      (info->horizontal_filter, info->horizontal_scale);
+}
+
+static int stbir__get_total_vertical_coefficients(stbir__info* info)
+{
+    return info->vertical_num_contributors
+         * stbir__get_coefficient_width      (info->vertical_filter, info->vertical_scale);
+}
+
+static stbir__contributors* stbir__get_contributor(stbir__contributors* contributors, int n)
+{
+    return &contributors[n];
+}
+
+// For perf reasons this code is duplicated in stbir__resample_horizontal_upsample/downsample,
+// if you change it here change it there too.
+static float* stbir__get_coefficient(float* coefficients, stbir_filter filter, float scale, int n, int c)
+{
+    int width = stbir__get_coefficient_width(filter, scale);
+    return &coefficients[width*n + c];
+}
+
+static int stbir__edge_wrap_slow(stbir_edge edge, int n, int max)
+{
+    switch (edge)
+    {
+    case STBIR_EDGE_ZERO:
+        return 0; // we'll decode the wrong pixel here, and then overwrite with 0s later
+
+    case STBIR_EDGE_CLAMP:
+        if (n < 0)
+            return 0;
+
+        if (n >= max)
+            return max - 1;
+
+        return n; // NOTREACHED
+
+    case STBIR_EDGE_REFLECT:
+    {
+        if (n < 0)
+        {
+            if (n < max)
+                return -n;
+            else
+                return max - 1;
+        }
+
+        if (n >= max)
+        {
+            int max2 = max * 2;
+            if (n >= max2)
+                return 0;
+            else
+                return max2 - n - 1;
+        }
+
+        return n; // NOTREACHED
+    }
+
+    case STBIR_EDGE_WRAP:
+        if (n >= 0)
+            return (n % max);
+        else
+        {
+            int m = (-n) % max;
+
+            if (m != 0)
+                m = max - m;
+
+            return (m);
+        }
+        return n;  // NOTREACHED
+
+    default:
+        STBIR__UNIMPLEMENTED("Unimplemented edge type");
+        return 0;
+    }
+}
+
+stbir__inline static int stbir__edge_wrap(stbir_edge edge, int n, int max)
+{
+    // avoid per-pixel switch
+    if (n >= 0 && n < max)
+        return n;
+    return stbir__edge_wrap_slow(edge, n, max);
+}
+
+// What input pixels contribute to this output pixel?
+static void stbir__calculate_sample_range_upsample(int n, float out_filter_radius, float scale_ratio, float out_shift, int* in_first_pixel, int* in_last_pixel, float* in_center_of_out)
+{
+    float out_pixel_center = (float)n + 0.5f;
+    float out_pixel_influence_lowerbound = out_pixel_center - out_filter_radius;
+    float out_pixel_influence_upperbound = out_pixel_center + out_filter_radius;
+
+    float in_pixel_influence_lowerbound = (out_pixel_influence_lowerbound + out_shift) / scale_ratio;
+    float in_pixel_influence_upperbound = (out_pixel_influence_upperbound + out_shift) / scale_ratio;
+
+    *in_center_of_out = (out_pixel_center + out_shift) / scale_ratio;
+    *in_first_pixel = (int)(floor(in_pixel_influence_lowerbound + 0.5));
+    *in_last_pixel = (int)(floor(in_pixel_influence_upperbound - 0.5));
+}
+
+// What output pixels does this input pixel contribute to?
+static void stbir__calculate_sample_range_downsample(int n, float in_pixels_radius, float scale_ratio, float out_shift, int* out_first_pixel, int* out_last_pixel, float* out_center_of_in)
+{
+    float in_pixel_center = (float)n + 0.5f;
+    float in_pixel_influence_lowerbound = in_pixel_center - in_pixels_radius;
+    float in_pixel_influence_upperbound = in_pixel_center + in_pixels_radius;
+
+    float out_pixel_influence_lowerbound = in_pixel_influence_lowerbound * scale_ratio - out_shift;
+    float out_pixel_influence_upperbound = in_pixel_influence_upperbound * scale_ratio - out_shift;
+
+    *out_center_of_in = in_pixel_center * scale_ratio - out_shift;
+    *out_first_pixel = (int)(floor(out_pixel_influence_lowerbound + 0.5));
+    *out_last_pixel = (int)(floor(out_pixel_influence_upperbound - 0.5));
+}
+
+static void stbir__calculate_coefficients_upsample(stbir__info* stbir_info, stbir_filter filter, float scale, int in_first_pixel, int in_last_pixel, float in_center_of_out, stbir__contributors* contributor, float* coefficient_group)
+{
+    int i;
+    float total_filter = 0;
+    float filter_scale;
+
+    STBIR__DEBUG_ASSERT(in_last_pixel - in_first_pixel <= (int)ceil(stbir__filter_info_table[filter].support(1/scale) * 2)); // Taken directly from stbir__get_coefficient_width() which we can't call because we don't know if we're horizontal or vertical.
+
+    contributor->n0 = in_first_pixel;
+    contributor->n1 = in_last_pixel;
+
+    STBIR__DEBUG_ASSERT(contributor->n1 >= contributor->n0);
+
+    for (i = 0; i <= in_last_pixel - in_first_pixel; i++)
+    {
+        float in_pixel_center = (float)(i + in_first_pixel) + 0.5f;
+        coefficient_group[i] = stbir__filter_info_table[filter].kernel(in_center_of_out - in_pixel_center, 1 / scale);
+
+        // If the coefficient is zero, skip it. (Don't do the <0 check here, we want the influence of those outside pixels.)
+        if (i == 0 && !coefficient_group[i])
+        {
+            contributor->n0 = ++in_first_pixel;
+            i--;
+            continue;
+        }
+
+        total_filter += coefficient_group[i];
+    }
+
+    STBIR__DEBUG_ASSERT(stbir__filter_info_table[filter].kernel((float)(in_last_pixel + 1) + 0.5f - in_center_of_out, 1/scale) == 0);
+
+    STBIR__DEBUG_ASSERT(total_filter > 0.9);
+    STBIR__DEBUG_ASSERT(total_filter < 1.1f); // Make sure it's not way off.
+
+    // Make sure the sum of all coefficients is 1.
+    filter_scale = 1 / total_filter;
+
+    for (i = 0; i <= in_last_pixel - in_first_pixel; i++)
+        coefficient_group[i] *= filter_scale;
+
+    for (i = in_last_pixel - in_first_pixel; i >= 0; i--)
+    {
+        if (coefficient_group[i])
+            break;
+
+        // This line has no weight. We can skip it.
+        contributor->n1 = contributor->n0 + i - 1;
+    }
+}
+
+static void stbir__calculate_coefficients_downsample(stbir__info* stbir_info, stbir_filter filter, float scale_ratio, int out_first_pixel, int out_last_pixel, float out_center_of_in, stbir__contributors* contributor, float* coefficient_group)
+{
+    int i;
+
+     STBIR__DEBUG_ASSERT(out_last_pixel - out_first_pixel <= (int)ceil(stbir__filter_info_table[filter].support(scale_ratio) * 2)); // Taken directly from stbir__get_coefficient_width() which we can't call because we don't know if we're horizontal or vertical.
+
+    contributor->n0 = out_first_pixel;
+    contributor->n1 = out_last_pixel;
+
+    STBIR__DEBUG_ASSERT(contributor->n1 >= contributor->n0);
+
+    for (i = 0; i <= out_last_pixel - out_first_pixel; i++)
+    {
+        float out_pixel_center = (float)(i + out_first_pixel) + 0.5f;
+        float x = out_pixel_center - out_center_of_in;
+        coefficient_group[i] = stbir__filter_info_table[filter].kernel(x, scale_ratio) * scale_ratio;
+    }
+
+    STBIR__DEBUG_ASSERT(stbir__filter_info_table[filter].kernel((float)(out_last_pixel + 1) + 0.5f - out_center_of_in, scale_ratio) == 0);
+
+    for (i = out_last_pixel - out_first_pixel; i >= 0; i--)
+    {
+        if (coefficient_group[i])
+            break;
+
+        // This line has no weight. We can skip it.
+        contributor->n1 = contributor->n0 + i - 1;
+    }
+}
+
+static void stbir__normalize_downsample_coefficients(stbir__info* stbir_info, stbir__contributors* contributors, float* coefficients, stbir_filter filter, float scale_ratio, float shift, int input_size, int output_size)
+{
+    int num_contributors = stbir__get_contributors(scale_ratio, filter, input_size, output_size);
+    int num_coefficients = stbir__get_coefficient_width(filter, scale_ratio);
+    int i, j;
+    int skip;
+
+    for (i = 0; i < output_size; i++)
+    {
+        float scale;
+        float total = 0;
+
+        for (j = 0; j < num_contributors; j++)
+        {
+            if (i >= contributors[j].n0 && i <= contributors[j].n1)
+            {
+                float coefficient = *stbir__get_coefficient(coefficients, filter, scale_ratio, j, i - contributors[j].n0);
+                total += coefficient;
+            }
+            else if (i < contributors[j].n0)
+                break;
+        }
+
+        STBIR__DEBUG_ASSERT(total > 0.9f);
+        STBIR__DEBUG_ASSERT(total < 1.1f);
+
+        scale = 1 / total;
+
+        for (j = 0; j < num_contributors; j++)
+        {
+            if (i >= contributors[j].n0 && i <= contributors[j].n1)
+                *stbir__get_coefficient(coefficients, filter, scale_ratio, j, i - contributors[j].n0) *= scale;
+            else if (i < contributors[j].n0)
+                break;
+        }
+    }
+
+    // Optimize: Skip zero coefficients and contributions outside of image bounds.
+    // Do this after normalizing because normalization depends on the n0/n1 values.
+    for (j = 0; j < num_contributors; j++)
+    {
+        int range, max, width;
+
+        skip = 0;
+        while (*stbir__get_coefficient(coefficients, filter, scale_ratio, j, skip) == 0)
+            skip++;
+
+        contributors[j].n0 += skip;
+
+        while (contributors[j].n0 < 0)
+        {
+            contributors[j].n0++;
+            skip++;
+        }
+
+        range = contributors[j].n1 - contributors[j].n0 + 1;
+        max = stbir__min(num_coefficients, range);
+
+        width = stbir__get_coefficient_width(filter, scale_ratio);
+        for (i = 0; i < max; i++)
+        {
+            if (i + skip >= width)
+                break;
+
+            *stbir__get_coefficient(coefficients, filter, scale_ratio, j, i) = *stbir__get_coefficient(coefficients, filter, scale_ratio, j, i + skip);
+        }
+
+        continue;
+    }
+
+    // Using min to avoid writing into invalid pixels.
+    for (i = 0; i < num_contributors; i++)
+        contributors[i].n1 = stbir__min(contributors[i].n1, output_size - 1);
+}
+
+// Each scan line uses the same kernel values so we should calculate the kernel
+// values once and then we can use them for every scan line.
+static void stbir__calculate_filters(stbir__info* stbir_info, stbir__contributors* contributors, float* coefficients, stbir_filter filter, float scale_ratio, float shift, int input_size, int output_size)
+{
+    int n;
+    int total_contributors = stbir__get_contributors(scale_ratio, filter, input_size, output_size);
+
+    if (stbir__use_upsampling(scale_ratio))
+    {
+        float out_pixels_radius = stbir__filter_info_table[filter].support(1 / scale_ratio) * scale_ratio;
+
+        // Looping through out pixels
+        for (n = 0; n < total_contributors; n++)
+        {
+            float in_center_of_out; // Center of the current out pixel in the in pixel space
+            int in_first_pixel, in_last_pixel;
+
+            stbir__calculate_sample_range_upsample(n, out_pixels_radius, scale_ratio, shift, &in_first_pixel, &in_last_pixel, &in_center_of_out);
+
+            stbir__calculate_coefficients_upsample(stbir_info, filter, scale_ratio, in_first_pixel, in_last_pixel, in_center_of_out, stbir__get_contributor(contributors, n), stbir__get_coefficient(coefficients, filter, scale_ratio, n, 0));
+        }
+    }
+    else
+    {
+        float in_pixels_radius = stbir__filter_info_table[filter].support(scale_ratio) / scale_ratio;
+
+        // Looping through in pixels
+        for (n = 0; n < total_contributors; n++)
+        {
+            float out_center_of_in; // Center of the current out pixel in the in pixel space
+            int out_first_pixel, out_last_pixel;
+            int n_adjusted = n - stbir__get_filter_pixel_margin(filter, scale_ratio);
+
+            stbir__calculate_sample_range_downsample(n_adjusted, in_pixels_radius, scale_ratio, shift, &out_first_pixel, &out_last_pixel, &out_center_of_in);
+
+            stbir__calculate_coefficients_downsample(stbir_info, filter, scale_ratio, out_first_pixel, out_last_pixel, out_center_of_in, stbir__get_contributor(contributors, n), stbir__get_coefficient(coefficients, filter, scale_ratio, n, 0));
+        }
+
+        stbir__normalize_downsample_coefficients(stbir_info, contributors, coefficients, filter, scale_ratio, shift, input_size, output_size);
+    }
+}
+
+static float* stbir__get_decode_buffer(stbir__info* stbir_info)
+{
+    // The 0 index of the decode buffer starts after the margin. This makes
+    // it okay to use negative indexes on the decode buffer.
+    return &stbir_info->decode_buffer[stbir_info->horizontal_filter_pixel_margin * stbir_info->channels];
+}
+
+#define STBIR__DECODE(type, colorspace) ((type) * (STBIR_MAX_COLORSPACES) + (colorspace))
+
+static void stbir__decode_scanline(stbir__info* stbir_info, int n)
+{
+    int c;
+    int channels = stbir_info->channels;
+    int alpha_channel = stbir_info->alpha_channel;
+    int type = stbir_info->type;
+    int colorspace = stbir_info->colorspace;
+    int input_w = stbir_info->input_w;
+    int input_stride_bytes = stbir_info->input_stride_bytes;
+    float* decode_buffer = stbir__get_decode_buffer(stbir_info);
+    stbir_edge edge_horizontal = stbir_info->edge_horizontal;
+    stbir_edge edge_vertical = stbir_info->edge_vertical;
+    int in_buffer_row_offset = stbir__edge_wrap(edge_vertical, n, stbir_info->input_h) * input_stride_bytes;
+    const void* input_data = (char *) stbir_info->input_data + in_buffer_row_offset;
+    int max_x = input_w + stbir_info->horizontal_filter_pixel_margin;
+    int decode = STBIR__DECODE(type, colorspace);
+
+    int x = -stbir_info->horizontal_filter_pixel_margin;
+
+    // special handling for STBIR_EDGE_ZERO because it needs to return an item that doesn't appear in the input,
+    // and we want to avoid paying overhead on every pixel if not STBIR_EDGE_ZERO
+    if (edge_vertical == STBIR_EDGE_ZERO && (n < 0 || n >= stbir_info->input_h))
+    {
+        for (; x < max_x; x++)
+            for (c = 0; c < channels; c++)
+                decode_buffer[x*channels + c] = 0;
+        return;
+    }
+
+    switch (decode)
+    {
+    case STBIR__DECODE(STBIR_TYPE_UINT8, STBIR_COLORSPACE_LINEAR):
+        for (; x < max_x; x++)
+        {
+            int decode_pixel_index = x * channels;
+            int input_pixel_index = stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
+            for (c = 0; c < channels; c++)
+                decode_buffer[decode_pixel_index + c] = ((float)((const unsigned char*)input_data)[input_pixel_index + c]) / 255;
+        }
+        break;
+
+    case STBIR__DECODE(STBIR_TYPE_UINT8, STBIR_COLORSPACE_SRGB):
+        for (; x < max_x; x++)
+        {
+            int decode_pixel_index = x * channels;
+            int input_pixel_index = stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
+            for (c = 0; c < channels; c++)
+                decode_buffer[decode_pixel_index + c] = stbir__srgb_uchar_to_linear_float[((const unsigned char*)input_data)[input_pixel_index + c]];
+
+            if (!(stbir_info->flags&STBIR_FLAG_ALPHA_USES_COLORSPACE))
+                decode_buffer[decode_pixel_index + alpha_channel] = ((float)((const unsigned char*)input_data)[input_pixel_index + alpha_channel]) / 255;
+        }
+        break;
+
+    case STBIR__DECODE(STBIR_TYPE_UINT16, STBIR_COLORSPACE_LINEAR):
+        for (; x < max_x; x++)
+        {
+            int decode_pixel_index = x * channels;
+            int input_pixel_index = stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
+            for (c = 0; c < channels; c++)
+                decode_buffer[decode_pixel_index + c] = ((float)((const unsigned short*)input_data)[input_pixel_index + c]) / 65535;
+        }
+        break;
+
+    case STBIR__DECODE(STBIR_TYPE_UINT16, STBIR_COLORSPACE_SRGB):
+        for (; x < max_x; x++)
+        {
+            int decode_pixel_index = x * channels;
+            int input_pixel_index = stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
+            for (c = 0; c < channels; c++)
+                decode_buffer[decode_pixel_index + c] = stbir__srgb_to_linear(((float)((const unsigned short*)input_data)[input_pixel_index + c]) / 65535);
+
+            if (!(stbir_info->flags&STBIR_FLAG_ALPHA_USES_COLORSPACE))
+                decode_buffer[decode_pixel_index + alpha_channel] = ((float)((const unsigned short*)input_data)[input_pixel_index + alpha_channel]) / 65535;
+        }
+        break;
+
+    case STBIR__DECODE(STBIR_TYPE_UINT32, STBIR_COLORSPACE_LINEAR):
+        for (; x < max_x; x++)
+        {
+            int decode_pixel_index = x * channels;
+            int input_pixel_index = stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
+            for (c = 0; c < channels; c++)
+                decode_buffer[decode_pixel_index + c] = (float)(((double)((const unsigned int*)input_data)[input_pixel_index + c]) / 4294967295);
+        }
+        break;
+
+    case STBIR__DECODE(STBIR_TYPE_UINT32, STBIR_COLORSPACE_SRGB):
+        for (; x < max_x; x++)
+        {
+            int decode_pixel_index = x * channels;
+            int input_pixel_index = stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
+            for (c = 0; c < channels; c++)
+                decode_buffer[decode_pixel_index + c] = stbir__srgb_to_linear((float)(((double)((const unsigned int*)input_data)[input_pixel_index + c]) / 4294967295));
+
+            if (!(stbir_info->flags&STBIR_FLAG_ALPHA_USES_COLORSPACE))
+                decode_buffer[decode_pixel_index + alpha_channel] = (float)(((double)((const unsigned int*)input_data)[input_pixel_index + alpha_channel]) / 4294967295);
+        }
+        break;
+
+    case STBIR__DECODE(STBIR_TYPE_FLOAT, STBIR_COLORSPACE_LINEAR):
+        for (; x < max_x; x++)
+        {
+            int decode_pixel_index = x * channels;
+            int input_pixel_index = stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
+            for (c = 0; c < channels; c++)
+                decode_buffer[decode_pixel_index + c] = ((const float*)input_data)[input_pixel_index + c];
+        }
+        break;
+
+    case STBIR__DECODE(STBIR_TYPE_FLOAT, STBIR_COLORSPACE_SRGB):
+        for (; x < max_x; x++)
+        {
+            int decode_pixel_index = x * channels;
+            int input_pixel_index = stbir__edge_wrap(edge_horizontal, x, input_w) * channels;
+            for (c = 0; c < channels; c++)
+                decode_buffer[decode_pixel_index + c] = stbir__srgb_to_linear(((const float*)input_data)[input_pixel_index + c]);
+
+            if (!(stbir_info->flags&STBIR_FLAG_ALPHA_USES_COLORSPACE))
+                decode_buffer[decode_pixel_index + alpha_channel] = ((const float*)input_data)[input_pixel_index + alpha_channel];
+        }
+
+        break;
+
+    default:
+        STBIR__UNIMPLEMENTED("Unknown type/colorspace/channels combination.");
+        break;
+    }
+
+    if (!(stbir_info->flags & STBIR_FLAG_ALPHA_PREMULTIPLIED))
+    {
+        for (x = -stbir_info->horizontal_filter_pixel_margin; x < max_x; x++)
+        {
+            int decode_pixel_index = x * channels;
+
+            // If the alpha value is 0 it will clobber the color values. Make sure it's not.
+            float alpha = decode_buffer[decode_pixel_index + alpha_channel];
+#ifndef STBIR_NO_ALPHA_EPSILON
+            if (stbir_info->type != STBIR_TYPE_FLOAT) {
+                alpha += STBIR_ALPHA_EPSILON;
+                decode_buffer[decode_pixel_index + alpha_channel] = alpha;
+            }
+#endif
+            for (c = 0; c < channels; c++)
+            {
+                if (c == alpha_channel)
+                    continue;
+
+                decode_buffer[decode_pixel_index + c] *= alpha;
+            }
+        }
+    }
+
+    if (edge_horizontal == STBIR_EDGE_ZERO)
+    {
+        for (x = -stbir_info->horizontal_filter_pixel_margin; x < 0; x++)
+        {
+            for (c = 0; c < channels; c++)
+                decode_buffer[x*channels + c] = 0;
+        }
+        for (x = input_w; x < max_x; x++)
+        {
+            for (c = 0; c < channels; c++)
+                decode_buffer[x*channels + c] = 0;
+        }
+    }
+}
+
+static float* stbir__get_ring_buffer_entry(float* ring_buffer, int index, int ring_buffer_length)
+{
+    return &ring_buffer[index * ring_buffer_length];
+}
+
+static float* stbir__add_empty_ring_buffer_entry(stbir__info* stbir_info, int n)
+{
+    int ring_buffer_index;
+    float* ring_buffer;
+
+    if (stbir_info->ring_buffer_begin_index < 0)
+    {
+        ring_buffer_index = stbir_info->ring_buffer_begin_index = 0;
+        stbir_info->ring_buffer_first_scanline = n;
+    }
+    else
+    {
+        ring_buffer_index = (stbir_info->ring_buffer_begin_index + (stbir_info->ring_buffer_last_scanline - stbir_info->ring_buffer_first_scanline) + 1) % stbir_info->vertical_filter_pixel_width;
+        STBIR__DEBUG_ASSERT(ring_buffer_index != stbir_info->ring_buffer_begin_index);
+    }
+
+    ring_buffer = stbir__get_ring_buffer_entry(stbir_info->ring_buffer, ring_buffer_index, stbir_info->ring_buffer_length_bytes / sizeof(float));
+    memset(ring_buffer, 0, stbir_info->ring_buffer_length_bytes);
+
+    stbir_info->ring_buffer_last_scanline = n;
+
+    return ring_buffer;
+}
+
+
+static void stbir__resample_horizontal_upsample(stbir__info* stbir_info, int n, float* output_buffer)
+{
+    int x, k;
+    int output_w = stbir_info->output_w;
+    int kernel_pixel_width = stbir_info->horizontal_filter_pixel_width;
+    int channels = stbir_info->channels;
+    float* decode_buffer = stbir__get_decode_buffer(stbir_info);
+    stbir__contributors* horizontal_contributors = stbir_info->horizontal_contributors;
+    float* horizontal_coefficients = stbir_info->horizontal_coefficients;
+    int coefficient_width = stbir_info->horizontal_coefficient_width;
+
+    for (x = 0; x < output_w; x++)
+    {
+        int n0 = horizontal_contributors[x].n0;
+        int n1 = horizontal_contributors[x].n1;
+
+        int out_pixel_index = x * channels;
+        int coefficient_group = coefficient_width * x;
+        int coefficient_counter = 0;
+
+        STBIR__DEBUG_ASSERT(n1 >= n0);
+        STBIR__DEBUG_ASSERT(n0 >= -stbir_info->horizontal_filter_pixel_margin);
+        STBIR__DEBUG_ASSERT(n1 >= -stbir_info->horizontal_filter_pixel_margin);
+        STBIR__DEBUG_ASSERT(n0 < stbir_info->input_w + stbir_info->horizontal_filter_pixel_margin);
+        STBIR__DEBUG_ASSERT(n1 < stbir_info->input_w + stbir_info->horizontal_filter_pixel_margin);
+
+        switch (channels) {
+            case 1:
+                for (k = n0; k <= n1; k++)
+                {
+                    int in_pixel_index = k * 1;
+                    float coefficient = horizontal_coefficients[coefficient_group + coefficient_counter++];
+                    STBIR__DEBUG_ASSERT(coefficient != 0);
+                    output_buffer[out_pixel_index + 0] += decode_buffer[in_pixel_index + 0] * coefficient;
+                }
+                break;
+            case 2:
+                for (k = n0; k <= n1; k++)
+                {
+                    int in_pixel_index = k * 2;
+                    float coefficient = horizontal_coefficients[coefficient_group + coefficient_counter++];
+                    STBIR__DEBUG_ASSERT(coefficient != 0);
+                    output_buffer[out_pixel_index + 0] += decode_buffer[in_pixel_index + 0] * coefficient;
+                    output_buffer[out_pixel_index + 1] += decode_buffer[in_pixel_index + 1] * coefficient;
+                }
+                break;
+            case 3:
+                for (k = n0; k <= n1; k++)
+                {
+                    int in_pixel_index = k * 3;
+                    float coefficient = horizontal_coefficients[coefficient_group + coefficient_counter++];
+                    STBIR__DEBUG_ASSERT(coefficient != 0);
+                    output_buffer[out_pixel_index + 0] += decode_buffer[in_pixel_index + 0] * coefficient;
+                    output_buffer[out_pixel_index + 1] += decode_buffer[in_pixel_index + 1] * coefficient;
+                    output_buffer[out_pixel_index + 2] += decode_buffer[in_pixel_index + 2] * coefficient;
+                }
+                break;
+            case 4:
+                for (k = n0; k <= n1; k++)
+                {
+                    int in_pixel_index = k * 4;
+                    float coefficient = horizontal_coefficients[coefficient_group + coefficient_counter++];
+                    STBIR__DEBUG_ASSERT(coefficient != 0);
+                    output_buffer[out_pixel_index + 0] += decode_buffer[in_pixel_index + 0] * coefficient;
+                    output_buffer[out_pixel_index + 1] += decode_buffer[in_pixel_index + 1] * coefficient;
+                    output_buffer[out_pixel_index + 2] += decode_buffer[in_pixel_index + 2] * coefficient;
+                    output_buffer[out_pixel_index + 3] += decode_buffer[in_pixel_index + 3] * coefficient;
+                }
+                break;
+            default:
+                for (k = n0; k <= n1; k++)
+                {
+                    int in_pixel_index = k * channels;
+                    float coefficient = horizontal_coefficients[coefficient_group + coefficient_counter++];
+                    int c;
+                    STBIR__DEBUG_ASSERT(coefficient != 0);
+                    for (c = 0; c < channels; c++)
+                        output_buffer[out_pixel_index + c] += decode_buffer[in_pixel_index + c] * coefficient;
+                }
+                break;
+        }
+    }
+}
+
+static void stbir__resample_horizontal_downsample(stbir__info* stbir_info, int n, float* output_buffer)
+{
+    int x, k;
+    int input_w = stbir_info->input_w;
+    int output_w = stbir_info->output_w;
+    int kernel_pixel_width = stbir_info->horizontal_filter_pixel_width;
+    int channels = stbir_info->channels;
+    float* decode_buffer = stbir__get_decode_buffer(stbir_info);
+    stbir__contributors* horizontal_contributors = stbir_info->horizontal_contributors;
+    float* horizontal_coefficients = stbir_info->horizontal_coefficients;
+    int coefficient_width = stbir_info->horizontal_coefficient_width;
+    int filter_pixel_margin = stbir_info->horizontal_filter_pixel_margin;
+    int max_x = input_w + filter_pixel_margin * 2;
+
+    STBIR__DEBUG_ASSERT(!stbir__use_width_upsampling(stbir_info));
+
+    switch (channels) {
+        case 1:
+            for (x = 0; x < max_x; x++)
+            {
+                int n0 = horizontal_contributors[x].n0;
+                int n1 = horizontal_contributors[x].n1;
+
+                int in_x = x - filter_pixel_margin;
+                int in_pixel_index = in_x * 1;
+                int max_n = n1;
+                int coefficient_group = coefficient_width * x;
+
+                for (k = n0; k <= max_n; k++)
+                {
+                    int out_pixel_index = k * 1;
+                    float coefficient = horizontal_coefficients[coefficient_group + k - n0];
+                    STBIR__DEBUG_ASSERT(coefficient != 0);
+                    output_buffer[out_pixel_index + 0] += decode_buffer[in_pixel_index + 0] * coefficient;
+                }
+            }
+            break;
+
+        case 2:
+            for (x = 0; x < max_x; x++)
+            {
+                int n0 = horizontal_contributors[x].n0;
+                int n1 = horizontal_contributors[x].n1;
+
+                int in_x = x - filter_pixel_margin;
+                int in_pixel_index = in_x * 2;
+                int max_n = n1;
+                int coefficient_group = coefficient_width * x;
+
+                for (k = n0; k <= max_n; k++)
+                {
+                    int out_pixel_index = k * 2;
+                    float coefficient = horizontal_coefficients[coefficient_group + k - n0];
+                    STBIR__DEBUG_ASSERT(coefficient != 0);
+                    output_buffer[out_pixel_index + 0] += decode_buffer[in_pixel_index + 0] * coefficient;
+                    output_buffer[out_pixel_index + 1] += decode_buffer[in_pixel_index + 1] * coefficient;
+                }
+            }
+            break;
+
+        case 3:
+            for (x = 0; x < max_x; x++)
+            {
+                int n0 = horizontal_contributors[x].n0;
+                int n1 = horizontal_contributors[x].n1;
+
+                int in_x = x - filter_pixel_margin;
+                int in_pixel_index = in_x * 3;
+                int max_n = n1;
+                int coefficient_group = coefficient_width * x;
+
+                for (k = n0; k <= max_n; k++)
+                {
+                    int out_pixel_index = k * 3;
+                    float coefficient = horizontal_coefficients[coefficient_group + k - n0];
+                    STBIR__DEBUG_ASSERT(coefficient != 0);
+                    output_buffer[out_pixel_index + 0] += decode_buffer[in_pixel_index + 0] * coefficient;
+                    output_buffer[out_pixel_index + 1] += decode_buffer[in_pixel_index + 1] * coefficient;
+                    output_buffer[out_pixel_index + 2] += decode_buffer[in_pixel_index + 2] * coefficient;
+                }
+            }
+            break;
+
+        case 4:
+            for (x = 0; x < max_x; x++)
+            {
+                int n0 = horizontal_contributors[x].n0;
+                int n1 = horizontal_contributors[x].n1;
+
+                int in_x = x - filter_pixel_margin;
+                int in_pixel_index = in_x * 4;
+                int max_n = n1;
+                int coefficient_group = coefficient_width * x;
+
+                for (k = n0; k <= max_n; k++)
+                {
+                    int out_pixel_index = k * 4;
+                    float coefficient = horizontal_coefficients[coefficient_group + k - n0];
+                    STBIR__DEBUG_ASSERT(coefficient != 0);
+                    output_buffer[out_pixel_index + 0] += decode_buffer[in_pixel_index + 0] * coefficient;
+                    output_buffer[out_pixel_index + 1] += decode_buffer[in_pixel_index + 1] * coefficient;
+                    output_buffer[out_pixel_index + 2] += decode_buffer[in_pixel_index + 2] * coefficient;
+                    output_buffer[out_pixel_index + 3] += decode_buffer[in_pixel_index + 3] * coefficient;
+                }
+            }
+            break;
+
+        default:
+            for (x = 0; x < max_x; x++)
+            {
+                int n0 = horizontal_contributors[x].n0;
+                int n1 = horizontal_contributors[x].n1;
+
+                int in_x = x - filter_pixel_margin;
+                int in_pixel_index = in_x * channels;
+                int max_n = n1;
+                int coefficient_group = coefficient_width * x;
+
+                for (k = n0; k <= max_n; k++)
+                {
+                    int c;
+                    int out_pixel_index = k * channels;
+                    float coefficient = horizontal_coefficients[coefficient_group + k - n0];
+                    STBIR__DEBUG_ASSERT(coefficient != 0);
+                    for (c = 0; c < channels; c++)
+                        output_buffer[out_pixel_index + c] += decode_buffer[in_pixel_index + c] * coefficient;
+                }
+            }
+            break;
+    }
+}
+
+static void stbir__decode_and_resample_upsample(stbir__info* stbir_info, int n)
+{
+    // Decode the nth scanline from the source image into the decode buffer.
+    stbir__decode_scanline(stbir_info, n);
+
+    // Now resample it into the ring buffer.
+    if (stbir__use_width_upsampling(stbir_info))
+        stbir__resample_horizontal_upsample(stbir_info, n, stbir__add_empty_ring_buffer_entry(stbir_info, n));
+    else
+        stbir__resample_horizontal_downsample(stbir_info, n, stbir__add_empty_ring_buffer_entry(stbir_info, n));
+
+    // Now it's sitting in the ring buffer ready to be used as source for the vertical sampling.
+}
+
+static void stbir__decode_and_resample_downsample(stbir__info* stbir_info, int n)
+{
+    // Decode the nth scanline from the source image into the decode buffer.
+    stbir__decode_scanline(stbir_info, n);
+
+    memset(stbir_info->horizontal_buffer, 0, stbir_info->output_w * stbir_info->channels * sizeof(float));
+
+    // Now resample it into the horizontal buffer.
+    if (stbir__use_width_upsampling(stbir_info))
+        stbir__resample_horizontal_upsample(stbir_info, n, stbir_info->horizontal_buffer);
+    else
+        stbir__resample_horizontal_downsample(stbir_info, n, stbir_info->horizontal_buffer);
+
+    // Now it's sitting in the horizontal buffer ready to be distributed into the ring buffers.
+}
+
+// Get the specified scan line from the ring buffer.
+static float* stbir__get_ring_buffer_scanline(int get_scanline, float* ring_buffer, int begin_index, int first_scanline, int ring_buffer_size, int ring_buffer_length)
+{
+    int ring_buffer_index = (begin_index + (get_scanline - first_scanline)) % ring_buffer_size;
+    return stbir__get_ring_buffer_entry(ring_buffer, ring_buffer_index, ring_buffer_length);
+}
+
+
+static void stbir__encode_scanline(stbir__info* stbir_info, int num_pixels, void *output_buffer, float *encode_buffer, int channels, int alpha_channel, int decode)
+{
+    int x;
+    int n;
+    int num_nonalpha;
+    stbir_uint16 nonalpha[STBIR_MAX_CHANNELS];
+
+    if (!(stbir_info->flags&STBIR_FLAG_ALPHA_PREMULTIPLIED))
+    {
+        for (x=0; x < num_pixels; ++x)
+        {
+            int pixel_index = x*channels;
+
+            float alpha = encode_buffer[pixel_index + alpha_channel];
+            float reciprocal_alpha = alpha ? 1.0f / alpha : 0;
+
+            // unrolling this produced a 1% slowdown upscaling a large RGBA linear-space image on my machine - stb
+            for (n = 0; n < channels; n++)
+                if (n != alpha_channel)
+                    encode_buffer[pixel_index + n] *= reciprocal_alpha;
+
+            // We added in a small epsilon to prevent the color channel from being deleted with zero alpha.
+            // Because we only add it for integer types, it will automatically be discarded on integer
+            // conversion, so we don't need to subtract it back out (which would be problematic for
+            // numeric precision reasons).
+        }
+    }
+
+    // build a table of all channels that need colorspace correction, so
+    // we don't perform colorspace correction on channels that don't need it.
+    for (x=0, num_nonalpha=0; x < channels; ++x)
+        if (x != alpha_channel || (stbir_info->flags & STBIR_FLAG_ALPHA_USES_COLORSPACE))
+            nonalpha[num_nonalpha++] = x;
+
+    #define STBIR__ROUND_INT(f)    ((int)          ((f)+0.5))
+    #define STBIR__ROUND_UINT(f)   ((stbir_uint32) ((f)+0.5))
+
+    #ifdef STBIR__SATURATE_INT
+    #define STBIR__ENCODE_LINEAR8(f)   stbir__saturate8 (STBIR__ROUND_INT((f) * 255  ))
+    #define STBIR__ENCODE_LINEAR16(f)  stbir__saturate16(STBIR__ROUND_INT((f) * 65535))
+    #else
+    #define STBIR__ENCODE_LINEAR8(f)   (unsigned char ) STBIR__ROUND_INT(stbir__saturate(f) * 255  )
+    #define STBIR__ENCODE_LINEAR16(f)  (unsigned short) STBIR__ROUND_INT(stbir__saturate(f) * 65535)
+    #endif
+
+    switch (decode)
+    {
+        case STBIR__DECODE(STBIR_TYPE_UINT8, STBIR_COLORSPACE_LINEAR):
+            for (x=0; x < num_pixels; ++x)
+            {
+                int pixel_index = x*channels;
+
+                for (n = 0; n < channels; n++)
+                {
+                    int index = pixel_index + n;
+                    ((unsigned char*)output_buffer)[index] = STBIR__ENCODE_LINEAR8(encode_buffer[index]);
+                }
+            }
+            break;
+
+        case STBIR__DECODE(STBIR_TYPE_UINT8, STBIR_COLORSPACE_SRGB):
+            for (x=0; x < num_pixels; ++x)
+            {
+                int pixel_index = x*channels;
+
+                for (n = 0; n < num_nonalpha; n++)
+                {
+                    int index = pixel_index + nonalpha[n];
+                    ((unsigned char*)output_buffer)[index] = stbir__linear_to_srgb_uchar(encode_buffer[index]);
+                }
+
+                if (!(stbir_info->flags & STBIR_FLAG_ALPHA_USES_COLORSPACE))
+                    ((unsigned char *)output_buffer)[pixel_index + alpha_channel] = STBIR__ENCODE_LINEAR8(encode_buffer[pixel_index+alpha_channel]);
+            }
+            break;
+
+        case STBIR__DECODE(STBIR_TYPE_UINT16, STBIR_COLORSPACE_LINEAR):
+            for (x=0; x < num_pixels; ++x)
+            {
+                int pixel_index = x*channels;
+
+                for (n = 0; n < channels; n++)
+                {
+                    int index = pixel_index + n;
+                    ((unsigned short*)output_buffer)[index] = STBIR__ENCODE_LINEAR16(encode_buffer[index]);
+                }
+            }
+            break;
+
+        case STBIR__DECODE(STBIR_TYPE_UINT16, STBIR_COLORSPACE_SRGB):
+            for (x=0; x < num_pixels; ++x)
+            {
+                int pixel_index = x*channels;
+
+                for (n = 0; n < num_nonalpha; n++)
+                {
+                    int index = pixel_index + nonalpha[n];
+                    ((unsigned short*)output_buffer)[index] = (unsigned short)STBIR__ROUND_INT(stbir__linear_to_srgb(stbir__saturate(encode_buffer[index])) * 65535);
+                }
+
+                if (!(stbir_info->flags&STBIR_FLAG_ALPHA_USES_COLORSPACE))
+                    ((unsigned short*)output_buffer)[pixel_index + alpha_channel] = STBIR__ENCODE_LINEAR16(encode_buffer[pixel_index + alpha_channel]);
+            }
+
+            break;
+
+        case STBIR__DECODE(STBIR_TYPE_UINT32, STBIR_COLORSPACE_LINEAR):
+            for (x=0; x < num_pixels; ++x)
+            {
+                int pixel_index = x*channels;
+
+                for (n = 0; n < channels; n++)
+                {
+                    int index = pixel_index + n;
+                    ((unsigned int*)output_buffer)[index] = (unsigned int)STBIR__ROUND_UINT(((double)stbir__saturate(encode_buffer[index])) * 4294967295);
+                }
+            }
+            break;
+
+        case STBIR__DECODE(STBIR_TYPE_UINT32, STBIR_COLORSPACE_SRGB):
+            for (x=0; x < num_pixels; ++x)
+            {
+                int pixel_index = x*channels;
+
+                for (n = 0; n < num_nonalpha; n++)
+                {
+                    int index = pixel_index + nonalpha[n];
+                    ((unsigned int*)output_buffer)[index] = (unsigned int)STBIR__ROUND_UINT(((double)stbir__linear_to_srgb(stbir__saturate(encode_buffer[index]))) * 4294967295);
+                }
+
+                if (!(stbir_info->flags&STBIR_FLAG_ALPHA_USES_COLORSPACE))
+                    ((unsigned int*)output_buffer)[pixel_index + alpha_channel] = (unsigned int)STBIR__ROUND_INT(((double)stbir__saturate(encode_buffer[pixel_index + alpha_channel])) * 4294967295);
+            }
+            break;
+
+        case STBIR__DECODE(STBIR_TYPE_FLOAT, STBIR_COLORSPACE_LINEAR):
+            for (x=0; x < num_pixels; ++x)
+            {
+                int pixel_index = x*channels;
+
+                for (n = 0; n < channels; n++)
+                {
+                    int index = pixel_index + n;
+                    ((float*)output_buffer)[index] = encode_buffer[index];
+                }
+            }
+            break;
+
+        case STBIR__DECODE(STBIR_TYPE_FLOAT, STBIR_COLORSPACE_SRGB):
+            for (x=0; x < num_pixels; ++x)
+            {
+                int pixel_index = x*channels;
+
+                for (n = 0; n < num_nonalpha; n++)
+                {
+                    int index = pixel_index + nonalpha[n];
+                    ((float*)output_buffer)[index] = stbir__linear_to_srgb(encode_buffer[index]);
+                }
+
+                if (!(stbir_info->flags&STBIR_FLAG_ALPHA_USES_COLORSPACE))
+                    ((float*)output_buffer)[pixel_index + alpha_channel] = encode_buffer[pixel_index + alpha_channel];
+            }
+            break;
+
+        default:
+            STBIR__UNIMPLEMENTED("Unknown type/colorspace/channels combination.");
+            break;
+    }
+}
+
+static void stbir__resample_vertical_upsample(stbir__info* stbir_info, int n, int in_first_scanline, int in_last_scanline, float in_center_of_out)
+{
+    int x, k;
+    int output_w = stbir_info->output_w;
+    stbir__contributors* vertical_contributors = stbir_info->vertical_contributors;
+    float* vertical_coefficients = stbir_info->vertical_coefficients;
+    int channels = stbir_info->channels;
+    int alpha_channel = stbir_info->alpha_channel;
+    int type = stbir_info->type;
+    int colorspace = stbir_info->colorspace;
+    int kernel_pixel_width = stbir_info->vertical_filter_pixel_width;
+    void* output_data = stbir_info->output_data;
+    float* encode_buffer = stbir_info->encode_buffer;
+    int decode = STBIR__DECODE(type, colorspace);
+    int coefficient_width = stbir_info->vertical_coefficient_width;
+    int coefficient_counter;
+    int contributor = n;
+
+    float* ring_buffer = stbir_info->ring_buffer;
+    int ring_buffer_begin_index = stbir_info->ring_buffer_begin_index;
+    int ring_buffer_first_scanline = stbir_info->ring_buffer_first_scanline;
+    int ring_buffer_last_scanline = stbir_info->ring_buffer_last_scanline;
+    int ring_buffer_length = stbir_info->ring_buffer_length_bytes/sizeof(float);
+
+    int n0,n1, output_row_start;
+    int coefficient_group = coefficient_width * contributor;
+
+    n0 = vertical_contributors[contributor].n0;
+    n1 = vertical_contributors[contributor].n1;
+
+    output_row_start = n * stbir_info->output_stride_bytes;
+
+    STBIR__DEBUG_ASSERT(stbir__use_height_upsampling(stbir_info));
+
+    memset(encode_buffer, 0, output_w * sizeof(float) * channels);
+
+    // I tried reblocking this for better cache usage of encode_buffer
+    // (using x_outer, k, x_inner), but it lost speed. -- stb
+
+    coefficient_counter = 0;
+    switch (channels) {
+        case 1:
+            for (k = n0; k <= n1; k++)
+            {
+                int coefficient_index = coefficient_counter++;
+                float* ring_buffer_entry = stbir__get_ring_buffer_scanline(k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline, kernel_pixel_width, ring_buffer_length);
+                float coefficient = vertical_coefficients[coefficient_group + coefficient_index];
+                for (x = 0; x < output_w; ++x)
+                {
+                    int in_pixel_index = x * 1;
+                    encode_buffer[in_pixel_index + 0] += ring_buffer_entry[in_pixel_index + 0] * coefficient;
+                }
+            }
+            break;
+        case 2:
+            for (k = n0; k <= n1; k++)
+            {
+                int coefficient_index = coefficient_counter++;
+                float* ring_buffer_entry = stbir__get_ring_buffer_scanline(k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline, kernel_pixel_width, ring_buffer_length);
+                float coefficient = vertical_coefficients[coefficient_group + coefficient_index];
+                for (x = 0; x < output_w; ++x)
+                {
+                    int in_pixel_index = x * 2;
+                    encode_buffer[in_pixel_index + 0] += ring_buffer_entry[in_pixel_index + 0] * coefficient;
+                    encode_buffer[in_pixel_index + 1] += ring_buffer_entry[in_pixel_index + 1] * coefficient;
+                }
+            }
+            break;
+        case 3:
+            for (k = n0; k <= n1; k++)
+            {
+                int coefficient_index = coefficient_counter++;
+                float* ring_buffer_entry = stbir__get_ring_buffer_scanline(k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline, kernel_pixel_width, ring_buffer_length);
+                float coefficient = vertical_coefficients[coefficient_group + coefficient_index];
+                for (x = 0; x < output_w; ++x)
+                {
+                    int in_pixel_index = x * 3;
+                    encode_buffer[in_pixel_index + 0] += ring_buffer_entry[in_pixel_index + 0] * coefficient;
+                    encode_buffer[in_pixel_index + 1] += ring_buffer_entry[in_pixel_index + 1] * coefficient;
+                    encode_buffer[in_pixel_index + 2] += ring_buffer_entry[in_pixel_index + 2] * coefficient;
+                }
+            }
+            break;
+        case 4:
+            for (k = n0; k <= n1; k++)
+            {
+                int coefficient_index = coefficient_counter++;
+                float* ring_buffer_entry = stbir__get_ring_buffer_scanline(k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline, kernel_pixel_width, ring_buffer_length);
+                float coefficient = vertical_coefficients[coefficient_group + coefficient_index];
+                for (x = 0; x < output_w; ++x)
+                {
+                    int in_pixel_index = x * 4;
+                    encode_buffer[in_pixel_index + 0] += ring_buffer_entry[in_pixel_index + 0] * coefficient;
+                    encode_buffer[in_pixel_index + 1] += ring_buffer_entry[in_pixel_index + 1] * coefficient;
+                    encode_buffer[in_pixel_index + 2] += ring_buffer_entry[in_pixel_index + 2] * coefficient;
+                    encode_buffer[in_pixel_index + 3] += ring_buffer_entry[in_pixel_index + 3] * coefficient;
+                }
+            }
+            break;
+        default:
+            for (k = n0; k <= n1; k++)
+            {
+                int coefficient_index = coefficient_counter++;
+                float* ring_buffer_entry = stbir__get_ring_buffer_scanline(k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline, kernel_pixel_width, ring_buffer_length);
+                float coefficient = vertical_coefficients[coefficient_group + coefficient_index];
+                for (x = 0; x < output_w; ++x)
+                {
+                    int in_pixel_index = x * channels;
+                    int c;
+                    for (c = 0; c < channels; c++)
+                        encode_buffer[in_pixel_index + c] += ring_buffer_entry[in_pixel_index + c] * coefficient;
+                }
+            }
+            break;
+    }
+    stbir__encode_scanline(stbir_info, output_w, (char *) output_data + output_row_start, encode_buffer, channels, alpha_channel, decode);
+}
+
+static void stbir__resample_vertical_downsample(stbir__info* stbir_info, int n, int in_first_scanline, int in_last_scanline, float in_center_of_out)
+{
+    int x, k;
+    int output_w = stbir_info->output_w;
+    int output_h = stbir_info->output_h;
+    stbir__contributors* vertical_contributors = stbir_info->vertical_contributors;
+    float* vertical_coefficients = stbir_info->vertical_coefficients;
+    int channels = stbir_info->channels;
+    int kernel_pixel_width = stbir_info->vertical_filter_pixel_width;
+    void* output_data = stbir_info->output_data;
+    float* horizontal_buffer = stbir_info->horizontal_buffer;
+    int coefficient_width = stbir_info->vertical_coefficient_width;
+    int contributor = n + stbir_info->vertical_filter_pixel_margin;
+
+    float* ring_buffer = stbir_info->ring_buffer;
+    int ring_buffer_begin_index = stbir_info->ring_buffer_begin_index;
+    int ring_buffer_first_scanline = stbir_info->ring_buffer_first_scanline;
+    int ring_buffer_last_scanline = stbir_info->ring_buffer_last_scanline;
+    int ring_buffer_length = stbir_info->ring_buffer_length_bytes/sizeof(float);
+    int n0,n1;
+
+    n0 = vertical_contributors[contributor].n0;
+    n1 = vertical_contributors[contributor].n1;
+
+    STBIR__DEBUG_ASSERT(!stbir__use_height_upsampling(stbir_info));
+
+    for (k = n0; k <= n1; k++)
+    {
+        int coefficient_index = k - n0;
+        int coefficient_group = coefficient_width * contributor;
+        float coefficient = vertical_coefficients[coefficient_group + coefficient_index];
+
+        float* ring_buffer_entry = stbir__get_ring_buffer_scanline(k, ring_buffer, ring_buffer_begin_index, ring_buffer_first_scanline, kernel_pixel_width, ring_buffer_length);
+
+        switch (channels) {
+            case 1:
+                for (x = 0; x < output_w; x++)
+                {
+                    int in_pixel_index = x * 1;
+                    ring_buffer_entry[in_pixel_index + 0] += horizontal_buffer[in_pixel_index + 0] * coefficient;
+                }
+                break;
+            case 2:
+                for (x = 0; x < output_w; x++)
+                {
+                    int in_pixel_index = x * 2;
+                    ring_buffer_entry[in_pixel_index + 0] += horizontal_buffer[in_pixel_index + 0] * coefficient;
+                    ring_buffer_entry[in_pixel_index + 1] += horizontal_buffer[in_pixel_index + 1] * coefficient;
+                }
+                break;
+            case 3:
+                for (x = 0; x < output_w; x++)
+                {
+                    int in_pixel_index = x * 3;
+                    ring_buffer_entry[in_pixel_index + 0] += horizontal_buffer[in_pixel_index + 0] * coefficient;
+                    ring_buffer_entry[in_pixel_index + 1] += horizontal_buffer[in_pixel_index + 1] * coefficient;
+                    ring_buffer_entry[in_pixel_index + 2] += horizontal_buffer[in_pixel_index + 2] * coefficient;
+                }
+                break;
+            case 4:
+                for (x = 0; x < output_w; x++)
+                {
+                    int in_pixel_index = x * 4;
+                    ring_buffer_entry[in_pixel_index + 0] += horizontal_buffer[in_pixel_index + 0] * coefficient;
+                    ring_buffer_entry[in_pixel_index + 1] += horizontal_buffer[in_pixel_index + 1] * coefficient;
+                    ring_buffer_entry[in_pixel_index + 2] += horizontal_buffer[in_pixel_index + 2] * coefficient;
+                    ring_buffer_entry[in_pixel_index + 3] += horizontal_buffer[in_pixel_index + 3] * coefficient;
+                }
+                break;
+            default:
+                for (x = 0; x < output_w; x++)
+                {
+                    int in_pixel_index = x * channels;
+
+                    int c;
+                    for (c = 0; c < channels; c++)
+                        ring_buffer_entry[in_pixel_index + c] += horizontal_buffer[in_pixel_index + c] * coefficient;
+                }
+                break;
+        }
+    }
+}
+
+static void stbir__buffer_loop_upsample(stbir__info* stbir_info)
+{
+    int y;
+    float scale_ratio = stbir_info->vertical_scale;
+    float out_scanlines_radius = stbir__filter_info_table[stbir_info->vertical_filter].support(1/scale_ratio) * scale_ratio;
+
+    STBIR__DEBUG_ASSERT(stbir__use_height_upsampling(stbir_info));
+
+    for (y = 0; y < stbir_info->output_h; y++)
+    {
+        float in_center_of_out = 0; // Center of the current out scanline in the in scanline space
+        int in_first_scanline = 0, in_last_scanline = 0;
+
+        stbir__calculate_sample_range_upsample(y, out_scanlines_radius, scale_ratio, stbir_info->vertical_shift, &in_first_scanline, &in_last_scanline, &in_center_of_out);
+
+        STBIR__DEBUG_ASSERT(in_last_scanline - in_first_scanline <= stbir_info->vertical_filter_pixel_width);
+
+        if (stbir_info->ring_buffer_begin_index >= 0)
+        {
+            // Get rid of whatever we don't need anymore.
+            while (in_first_scanline > stbir_info->ring_buffer_first_scanline)
+            {
+                if (stbir_info->ring_buffer_first_scanline == stbir_info->ring_buffer_last_scanline)
+                {
+                    // We just popped the last scanline off the ring buffer.
+                    // Reset it to the empty state.
+                    stbir_info->ring_buffer_begin_index = -1;
+                    stbir_info->ring_buffer_first_scanline = 0;
+                    stbir_info->ring_buffer_last_scanline = 0;
+                    break;
+                }
+                else
+                {
+                    stbir_info->ring_buffer_first_scanline++;
+                    stbir_info->ring_buffer_begin_index = (stbir_info->ring_buffer_begin_index + 1) % stbir_info->vertical_filter_pixel_width;
+                }
+            }
+        }
+
+        // Load in new ones.
+        if (stbir_info->ring_buffer_begin_index < 0)
+            stbir__decode_and_resample_upsample(stbir_info, in_first_scanline);
+
+        while (in_last_scanline > stbir_info->ring_buffer_last_scanline)
+            stbir__decode_and_resample_upsample(stbir_info, stbir_info->ring_buffer_last_scanline + 1);
+
+        // Now all buffers should be ready to write a row of vertical sampling.
+        stbir__resample_vertical_upsample(stbir_info, y, in_first_scanline, in_last_scanline, in_center_of_out);
+
+        STBIR_PROGRESS_REPORT((float)y / stbir_info->output_h);
+    }
+}
+
+static void stbir__empty_ring_buffer(stbir__info* stbir_info, int first_necessary_scanline)
+{
+    int output_stride_bytes = stbir_info->output_stride_bytes;
+    int channels = stbir_info->channels;
+    int alpha_channel = stbir_info->alpha_channel;
+    int type = stbir_info->type;
+    int colorspace = stbir_info->colorspace;
+    int output_w = stbir_info->output_w;
+    void* output_data = stbir_info->output_data;
+    int decode = STBIR__DECODE(type, colorspace);
+
+    float* ring_buffer = stbir_info->ring_buffer;
+    int ring_buffer_length = stbir_info->ring_buffer_length_bytes/sizeof(float);
+
+    if (stbir_info->ring_buffer_begin_index >= 0)
+    {
+        // Get rid of whatever we don't need anymore.
+        while (first_necessary_scanline > stbir_info->ring_buffer_first_scanline)
+        {
+            if (stbir_info->ring_buffer_first_scanline >= 0 && stbir_info->ring_buffer_first_scanline < stbir_info->output_h)
+            {
+                int output_row_start = stbir_info->ring_buffer_first_scanline * output_stride_bytes;
+                float* ring_buffer_entry = stbir__get_ring_buffer_entry(ring_buffer, stbir_info->ring_buffer_begin_index, ring_buffer_length);
+                stbir__encode_scanline(stbir_info, output_w, (char *) output_data + output_row_start, ring_buffer_entry, channels, alpha_channel, decode);
+                STBIR_PROGRESS_REPORT((float)stbir_info->ring_buffer_first_scanline / stbir_info->output_h);
+            }
+
+            if (stbir_info->ring_buffer_first_scanline == stbir_info->ring_buffer_last_scanline)
+            {
+                // We just popped the last scanline off the ring buffer.
+                // Reset it to the empty state.
+                stbir_info->ring_buffer_begin_index = -1;
+                stbir_info->ring_buffer_first_scanline = 0;
+                stbir_info->ring_buffer_last_scanline = 0;
+                break;
+            }
+            else
+            {
+                stbir_info->ring_buffer_first_scanline++;
+                stbir_info->ring_buffer_begin_index = (stbir_info->ring_buffer_begin_index + 1) % stbir_info->vertical_filter_pixel_width;
+            }
+        }
+    }
+}
+
+static void stbir__buffer_loop_downsample(stbir__info* stbir_info)
+{
+    int y;
+    float scale_ratio = stbir_info->vertical_scale;
+    int output_h = stbir_info->output_h;
+    float in_pixels_radius = stbir__filter_info_table[stbir_info->vertical_filter].support(scale_ratio) / scale_ratio;
+    int pixel_margin = stbir_info->vertical_filter_pixel_margin;
+    int max_y = stbir_info->input_h + pixel_margin;
+
+    STBIR__DEBUG_ASSERT(!stbir__use_height_upsampling(stbir_info));
+
+    for (y = -pixel_margin; y < max_y; y++)
+    {
+        float out_center_of_in; // Center of the current out scanline in the in scanline space
+        int out_first_scanline, out_last_scanline;
+
+        stbir__calculate_sample_range_downsample(y, in_pixels_radius, scale_ratio, stbir_info->vertical_shift, &out_first_scanline, &out_last_scanline, &out_center_of_in);
+
+        STBIR__DEBUG_ASSERT(out_last_scanline - out_first_scanline <= stbir_info->vertical_filter_pixel_width);
+
+        if (out_last_scanline < 0 || out_first_scanline >= output_h)
+            continue;
+
+        stbir__empty_ring_buffer(stbir_info, out_first_scanline);
+
+        stbir__decode_and_resample_downsample(stbir_info, y);
+
+        // Load in new ones.
+        if (stbir_info->ring_buffer_begin_index < 0)
+            stbir__add_empty_ring_buffer_entry(stbir_info, out_first_scanline);
+
+        while (out_last_scanline > stbir_info->ring_buffer_last_scanline)
+            stbir__add_empty_ring_buffer_entry(stbir_info, stbir_info->ring_buffer_last_scanline + 1);
+
+        // Now the horizontal buffer is ready to write to all ring buffer rows.
+        stbir__resample_vertical_downsample(stbir_info, y, out_first_scanline, out_last_scanline, out_center_of_in);
+    }
+
+    stbir__empty_ring_buffer(stbir_info, stbir_info->output_h);
+}
+
+static void stbir__setup(stbir__info *info, int input_w, int input_h, int output_w, int output_h, int channels)
+{
+    info->input_w = input_w;
+    info->input_h = input_h;
+    info->output_w = output_w;
+    info->output_h = output_h;
+    info->channels = channels;
+}
+
+static void stbir__calculate_transform(stbir__info *info, float s0, float t0, float s1, float t1, float *transform)
+{
+    info->s0 = s0;
+    info->t0 = t0;
+    info->s1 = s1;
+    info->t1 = t1;
+
+    if (transform)
+    {
+        info->horizontal_scale = transform[0];
+        info->vertical_scale   = transform[1];
+        info->horizontal_shift = transform[2];
+        info->vertical_shift   = transform[3];
+    }
+    else
+    {
+        info->horizontal_scale = ((float)info->output_w / info->input_w) / (s1 - s0);
+        info->vertical_scale = ((float)info->output_h / info->input_h) / (t1 - t0);
+
+        info->horizontal_shift = s0 * info->input_w / (s1 - s0);
+        info->vertical_shift = t0 * info->input_h / (t1 - t0);
+    }
+}
+
+static void stbir__choose_filter(stbir__info *info, stbir_filter h_filter, stbir_filter v_filter)
+{
+    if (h_filter == 0)
+        h_filter = stbir__use_upsampling(info->horizontal_scale) ? STBIR_DEFAULT_FILTER_UPSAMPLE : STBIR_DEFAULT_FILTER_DOWNSAMPLE;
+    if (v_filter == 0)
+        v_filter = stbir__use_upsampling(info->vertical_scale)   ? STBIR_DEFAULT_FILTER_UPSAMPLE : STBIR_DEFAULT_FILTER_DOWNSAMPLE;
+    info->horizontal_filter = h_filter;
+    info->vertical_filter = v_filter;
+}
+
+static stbir_uint32 stbir__calculate_memory(stbir__info *info)
+{
+    int pixel_margin = stbir__get_filter_pixel_margin(info->horizontal_filter, info->horizontal_scale);
+    int filter_height = stbir__get_filter_pixel_width(info->vertical_filter, info->vertical_scale);
+
+    info->horizontal_num_contributors = stbir__get_contributors(info->horizontal_scale, info->horizontal_filter, info->input_w, info->output_w);
+    info->vertical_num_contributors   = stbir__get_contributors(info->vertical_scale  , info->vertical_filter  , info->input_h, info->output_h);
+
+    info->horizontal_contributors_size = info->horizontal_num_contributors * sizeof(stbir__contributors);
+    info->horizontal_coefficients_size = stbir__get_total_horizontal_coefficients(info) * sizeof(float);
+    info->vertical_contributors_size = info->vertical_num_contributors * sizeof(stbir__contributors);
+    info->vertical_coefficients_size = stbir__get_total_vertical_coefficients(info) * sizeof(float);
+    info->decode_buffer_size = (info->input_w + pixel_margin * 2) * info->channels * sizeof(float);
+    info->horizontal_buffer_size = info->output_w * info->channels * sizeof(float);
+    info->ring_buffer_size = info->output_w * info->channels * filter_height * sizeof(float);
+    info->encode_buffer_size = info->output_w * info->channels * sizeof(float);
+
+    STBIR_ASSERT(info->horizontal_filter != 0);
+    STBIR_ASSERT(info->horizontal_filter < STBIR__ARRAY_SIZE(stbir__filter_info_table)); // this now happens too late
+    STBIR_ASSERT(info->vertical_filter != 0);
+    STBIR_ASSERT(info->vertical_filter < STBIR__ARRAY_SIZE(stbir__filter_info_table)); // this now happens too late
+
+    if (stbir__use_height_upsampling(info))
+        // The horizontal buffer is for when we're downsampling the height and we
+        // can't output the result of sampling the decode buffer directly into the
+        // ring buffers.
+        info->horizontal_buffer_size = 0;
+    else
+        // The encode buffer is to retain precision in the height upsampling method
+        // and isn't used when height downsampling.
+        info->encode_buffer_size = 0;
+
+    return info->horizontal_contributors_size + info->horizontal_coefficients_size
+        + info->vertical_contributors_size + info->vertical_coefficients_size
+        + info->decode_buffer_size + info->horizontal_buffer_size
+        + info->ring_buffer_size + info->encode_buffer_size;
+}
+
+static int stbir__resize_allocated(stbir__info *info,
+    const void* input_data, int input_stride_in_bytes,
+    void* output_data, int output_stride_in_bytes,
+    int alpha_channel, stbir_uint32 flags, stbir_datatype type,
+    stbir_edge edge_horizontal, stbir_edge edge_vertical, stbir_colorspace colorspace,
+    void* tempmem, size_t tempmem_size_in_bytes)
+{
+    size_t memory_required = stbir__calculate_memory(info);
+
+    int width_stride_input = input_stride_in_bytes ? input_stride_in_bytes : info->channels * info->input_w * stbir__type_size[type];
+    int width_stride_output = output_stride_in_bytes ? output_stride_in_bytes : info->channels * info->output_w * stbir__type_size[type];
+
+#ifdef STBIR_DEBUG_OVERWRITE_TEST
+#define OVERWRITE_ARRAY_SIZE 8
+    unsigned char overwrite_output_before_pre[OVERWRITE_ARRAY_SIZE];
+    unsigned char overwrite_tempmem_before_pre[OVERWRITE_ARRAY_SIZE];
+    unsigned char overwrite_output_after_pre[OVERWRITE_ARRAY_SIZE];
+    unsigned char overwrite_tempmem_after_pre[OVERWRITE_ARRAY_SIZE];
+
+    size_t begin_forbidden = width_stride_output * (info->output_h - 1) + info->output_w * info->channels * stbir__type_size[type];
+    memcpy(overwrite_output_before_pre, &((unsigned char*)output_data)[-OVERWRITE_ARRAY_SIZE], OVERWRITE_ARRAY_SIZE);
+    memcpy(overwrite_output_after_pre, &((unsigned char*)output_data)[begin_forbidden], OVERWRITE_ARRAY_SIZE);
+    memcpy(overwrite_tempmem_before_pre, &((unsigned char*)tempmem)[-OVERWRITE_ARRAY_SIZE], OVERWRITE_ARRAY_SIZE);
+    memcpy(overwrite_tempmem_after_pre, &((unsigned char*)tempmem)[tempmem_size_in_bytes], OVERWRITE_ARRAY_SIZE);
+#endif
+
+    STBIR_ASSERT(info->channels >= 0);
+    STBIR_ASSERT(info->channels <= STBIR_MAX_CHANNELS);
+
+    if (info->channels < 0 || info->channels > STBIR_MAX_CHANNELS)
+        return 0;
+
+    STBIR_ASSERT(info->horizontal_filter < STBIR__ARRAY_SIZE(stbir__filter_info_table));
+    STBIR_ASSERT(info->vertical_filter < STBIR__ARRAY_SIZE(stbir__filter_info_table));
+
+    if (info->horizontal_filter >= STBIR__ARRAY_SIZE(stbir__filter_info_table))
+        return 0;
+    if (info->vertical_filter >= STBIR__ARRAY_SIZE(stbir__filter_info_table))
+        return 0;
+
+    if (alpha_channel < 0)
+        flags |= STBIR_FLAG_ALPHA_USES_COLORSPACE | STBIR_FLAG_ALPHA_PREMULTIPLIED;
+
+    if (!(flags&STBIR_FLAG_ALPHA_USES_COLORSPACE) || !(flags&STBIR_FLAG_ALPHA_PREMULTIPLIED))
+        STBIR_ASSERT(alpha_channel >= 0 && alpha_channel < info->channels);
+
+    if (alpha_channel >= info->channels)
+        return 0;
+
+    STBIR_ASSERT(tempmem);
+
+    if (!tempmem)
+        return 0;
+
+    STBIR_ASSERT(tempmem_size_in_bytes >= memory_required);
+
+    if (tempmem_size_in_bytes < memory_required)
+        return 0;
+
+    memset(tempmem, 0, tempmem_size_in_bytes);
+
+    info->input_data = input_data;
+    info->input_stride_bytes = width_stride_input;
+
+    info->output_data = output_data;
+    info->output_stride_bytes = width_stride_output;
+
+    info->alpha_channel = alpha_channel;
+    info->flags = flags;
+    info->type = type;
+    info->edge_horizontal = edge_horizontal;
+    info->edge_vertical = edge_vertical;
+    info->colorspace = colorspace;
+
+    info->horizontal_coefficient_width   = stbir__get_coefficient_width  (info->horizontal_filter, info->horizontal_scale);
+    info->vertical_coefficient_width     = stbir__get_coefficient_width  (info->vertical_filter  , info->vertical_scale  );
+    info->horizontal_filter_pixel_width  = stbir__get_filter_pixel_width (info->horizontal_filter, info->horizontal_scale);
+    info->vertical_filter_pixel_width    = stbir__get_filter_pixel_width (info->vertical_filter  , info->vertical_scale  );
+    info->horizontal_filter_pixel_margin = stbir__get_filter_pixel_margin(info->horizontal_filter, info->horizontal_scale);
+    info->vertical_filter_pixel_margin   = stbir__get_filter_pixel_margin(info->vertical_filter  , info->vertical_scale  );
+
+    info->ring_buffer_length_bytes = info->output_w * info->channels * sizeof(float);
+    info->decode_buffer_pixels = info->input_w + info->horizontal_filter_pixel_margin * 2;
+
+#define STBIR__NEXT_MEMPTR(current, newtype) (newtype*)(((unsigned char*)current) + current##_size)
+
+    info->horizontal_contributors = (stbir__contributors *) tempmem;
+    info->horizontal_coefficients = STBIR__NEXT_MEMPTR(info->horizontal_contributors, float);
+    info->vertical_contributors = STBIR__NEXT_MEMPTR(info->horizontal_coefficients, stbir__contributors);
+    info->vertical_coefficients = STBIR__NEXT_MEMPTR(info->vertical_contributors, float);
+    info->decode_buffer = STBIR__NEXT_MEMPTR(info->vertical_coefficients, float);
+
+    if (stbir__use_height_upsampling(info))
+    {
+        info->horizontal_buffer = NULL;
+        info->ring_buffer = STBIR__NEXT_MEMPTR(info->decode_buffer, float);
+        info->encode_buffer = STBIR__NEXT_MEMPTR(info->ring_buffer, float);
+
+        STBIR__DEBUG_ASSERT((size_t)STBIR__NEXT_MEMPTR(info->encode_buffer, unsigned char) == (size_t)tempmem + tempmem_size_in_bytes);
+    }
+    else
+    {
+        info->horizontal_buffer = STBIR__NEXT_MEMPTR(info->decode_buffer, float);
+        info->ring_buffer = STBIR__NEXT_MEMPTR(info->horizontal_buffer, float);
+        info->encode_buffer = NULL;
+
+        STBIR__DEBUG_ASSERT((size_t)STBIR__NEXT_MEMPTR(info->ring_buffer, unsigned char) == (size_t)tempmem + tempmem_size_in_bytes);
+    }
+
+#undef STBIR__NEXT_MEMPTR
+
+    // This signals that the ring buffer is empty
+    info->ring_buffer_begin_index = -1;
+
+    stbir__calculate_filters(info, info->horizontal_contributors, info->horizontal_coefficients, info->horizontal_filter, info->horizontal_scale, info->horizontal_shift, info->input_w, info->output_w);
+    stbir__calculate_filters(info, info->vertical_contributors, info->vertical_coefficients, info->vertical_filter, info->vertical_scale, info->vertical_shift, info->input_h, info->output_h);
+
+    STBIR_PROGRESS_REPORT(0);
+
+    if (stbir__use_height_upsampling(info))
+        stbir__buffer_loop_upsample(info);
+    else
+        stbir__buffer_loop_downsample(info);
+
+    STBIR_PROGRESS_REPORT(1);
+
+#ifdef STBIR_DEBUG_OVERWRITE_TEST
+    STBIR__DEBUG_ASSERT(memcmp(overwrite_output_before_pre, &((unsigned char*)output_data)[-OVERWRITE_ARRAY_SIZE], OVERWRITE_ARRAY_SIZE) == 0);
+    STBIR__DEBUG_ASSERT(memcmp(overwrite_output_after_pre, &((unsigned char*)output_data)[begin_forbidden], OVERWRITE_ARRAY_SIZE) == 0);
+    STBIR__DEBUG_ASSERT(memcmp(overwrite_tempmem_before_pre, &((unsigned char*)tempmem)[-OVERWRITE_ARRAY_SIZE], OVERWRITE_ARRAY_SIZE) == 0);
+    STBIR__DEBUG_ASSERT(memcmp(overwrite_tempmem_after_pre, &((unsigned char*)tempmem)[tempmem_size_in_bytes], OVERWRITE_ARRAY_SIZE) == 0);
+#endif
+
+    return 1;
+}
+
+
+static int stbir__resize_arbitrary(
+    void *alloc_context,
+    const void* input_data, int input_w, int input_h, int input_stride_in_bytes,
+    void* output_data, int output_w, int output_h, int output_stride_in_bytes,
+    float s0, float t0, float s1, float t1, float *transform,
+    int channels, int alpha_channel, stbir_uint32 flags, stbir_datatype type,
+    stbir_filter h_filter, stbir_filter v_filter,
+    stbir_edge edge_horizontal, stbir_edge edge_vertical, stbir_colorspace colorspace)
+{
+    stbir__info info;
+    int result;
+    size_t memory_required;
+    void* extra_memory;
+
+    stbir__setup(&info, input_w, input_h, output_w, output_h, channels);
+    stbir__calculate_transform(&info, s0,t0,s1,t1,transform);
+    stbir__choose_filter(&info, h_filter, v_filter);
+    memory_required = stbir__calculate_memory(&info);
+    extra_memory = STBIR_MALLOC(memory_required, alloc_context);
+
+    if (!extra_memory)
+        return 0;
+
+    result = stbir__resize_allocated(&info, input_data, input_stride_in_bytes,
+                                            output_data, output_stride_in_bytes, 
+                                            alpha_channel, flags, type,
+                                            edge_horizontal, edge_vertical,
+                                            colorspace, extra_memory, memory_required);
+
+    STBIR_FREE(extra_memory, alloc_context);
+
+    return result;
+}
+
+STBIRDEF int stbir_resize_uint8(     const unsigned char *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                           unsigned char *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                     int num_channels)
+{
+    return stbir__resize_arbitrary(NULL, input_pixels, input_w, input_h, input_stride_in_bytes,
+        output_pixels, output_w, output_h, output_stride_in_bytes,
+        0,0,1,1,NULL,num_channels,-1,0, STBIR_TYPE_UINT8, STBIR_FILTER_DEFAULT, STBIR_FILTER_DEFAULT,
+        STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_LINEAR);
+}
+
+STBIRDEF int stbir_resize_float(     const float *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                           float *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                     int num_channels)
+{
+    return stbir__resize_arbitrary(NULL, input_pixels, input_w, input_h, input_stride_in_bytes,
+        output_pixels, output_w, output_h, output_stride_in_bytes,
+        0,0,1,1,NULL,num_channels,-1,0, STBIR_TYPE_FLOAT, STBIR_FILTER_DEFAULT, STBIR_FILTER_DEFAULT,
+        STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_LINEAR);
+}
+
+STBIRDEF int stbir_resize_uint8_srgb(const unsigned char *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                           unsigned char *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                     int num_channels, int alpha_channel, int flags)
+{
+    return stbir__resize_arbitrary(NULL, input_pixels, input_w, input_h, input_stride_in_bytes,
+        output_pixels, output_w, output_h, output_stride_in_bytes,
+        0,0,1,1,NULL,num_channels,alpha_channel,flags, STBIR_TYPE_UINT8, STBIR_FILTER_DEFAULT, STBIR_FILTER_DEFAULT,
+        STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB);
+}
+
+STBIRDEF int stbir_resize_uint8_srgb_edgemode(const unsigned char *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                                    unsigned char *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                              int num_channels, int alpha_channel, int flags,
+                                              stbir_edge edge_wrap_mode)
+{
+    return stbir__resize_arbitrary(NULL, input_pixels, input_w, input_h, input_stride_in_bytes,
+        output_pixels, output_w, output_h, output_stride_in_bytes,
+        0,0,1,1,NULL,num_channels,alpha_channel,flags, STBIR_TYPE_UINT8, STBIR_FILTER_DEFAULT, STBIR_FILTER_DEFAULT,
+        edge_wrap_mode, edge_wrap_mode, STBIR_COLORSPACE_SRGB);
+}
+
+STBIRDEF int stbir_resize_uint8_generic( const unsigned char *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                               unsigned char *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                         int num_channels, int alpha_channel, int flags,
+                                         stbir_edge edge_wrap_mode, stbir_filter filter, stbir_colorspace space, 
+                                         void *alloc_context)
+{
+    return stbir__resize_arbitrary(alloc_context, input_pixels, input_w, input_h, input_stride_in_bytes,
+        output_pixels, output_w, output_h, output_stride_in_bytes,
+        0,0,1,1,NULL,num_channels,alpha_channel,flags, STBIR_TYPE_UINT8, filter, filter,
+        edge_wrap_mode, edge_wrap_mode, space);
+}
+
+STBIRDEF int stbir_resize_uint16_generic(const stbir_uint16 *input_pixels  , int input_w , int input_h , int input_stride_in_bytes,
+                                               stbir_uint16 *output_pixels , int output_w, int output_h, int output_stride_in_bytes,
+                                         int num_channels, int alpha_channel, int flags,
+                                         stbir_edge edge_wrap_mode, stbir_filter filter, stbir_colorspace space, 
+                                         void *alloc_context)
+{
+    return stbir__resize_arbitrary(alloc_context, input_pixels, input_w, input_h, input_stride_in_bytes,
+        output_pixels, output_w, output_h, output_stride_in_bytes,
+        0,0,1,1,NULL,num_channels,alpha_channel,flags, STBIR_TYPE_UINT16, filter, filter,
+        edge_wrap_mode, edge_wrap_mode, space);
+}
+
+
+STBIRDEF int stbir_resize_float_generic( const float *input_pixels         , int input_w , int input_h , int input_stride_in_bytes,
+                                               float *output_pixels        , int output_w, int output_h, int output_stride_in_bytes,
+                                         int num_channels, int alpha_channel, int flags,
+                                         stbir_edge edge_wrap_mode, stbir_filter filter, stbir_colorspace space, 
+                                         void *alloc_context)
+{
+    return stbir__resize_arbitrary(alloc_context, input_pixels, input_w, input_h, input_stride_in_bytes,
+        output_pixels, output_w, output_h, output_stride_in_bytes,
+        0,0,1,1,NULL,num_channels,alpha_channel,flags, STBIR_TYPE_FLOAT, filter, filter,
+        edge_wrap_mode, edge_wrap_mode, space);
+}
+
+
+STBIRDEF int stbir_resize(         const void *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                         void *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                   stbir_datatype datatype,
+                                   int num_channels, int alpha_channel, int flags,
+                                   stbir_edge edge_mode_horizontal, stbir_edge edge_mode_vertical, 
+                                   stbir_filter filter_horizontal,  stbir_filter filter_vertical,
+                                   stbir_colorspace space, void *alloc_context)
+{
+    return stbir__resize_arbitrary(alloc_context, input_pixels, input_w, input_h, input_stride_in_bytes,
+        output_pixels, output_w, output_h, output_stride_in_bytes,
+        0,0,1,1,NULL,num_channels,alpha_channel,flags, datatype, filter_horizontal, filter_vertical,
+        edge_mode_horizontal, edge_mode_vertical, space);
+}
+
+
+STBIRDEF int stbir_resize_subpixel(const void *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                         void *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                   stbir_datatype datatype,
+                                   int num_channels, int alpha_channel, int flags,
+                                   stbir_edge edge_mode_horizontal, stbir_edge edge_mode_vertical, 
+                                   stbir_filter filter_horizontal,  stbir_filter filter_vertical,
+                                   stbir_colorspace space, void *alloc_context,
+                                   float x_scale, float y_scale,
+                                   float x_offset, float y_offset)
+{
+    float transform[4];
+    transform[0] = x_scale;
+    transform[1] = y_scale;
+    transform[2] = x_offset;
+    transform[3] = y_offset;
+    return stbir__resize_arbitrary(alloc_context, input_pixels, input_w, input_h, input_stride_in_bytes,
+        output_pixels, output_w, output_h, output_stride_in_bytes,
+        0,0,1,1,transform,num_channels,alpha_channel,flags, datatype, filter_horizontal, filter_vertical,
+        edge_mode_horizontal, edge_mode_vertical, space);
+}
+
+STBIRDEF int stbir_resize_region(  const void *input_pixels , int input_w , int input_h , int input_stride_in_bytes,
+                                         void *output_pixels, int output_w, int output_h, int output_stride_in_bytes,
+                                   stbir_datatype datatype,
+                                   int num_channels, int alpha_channel, int flags,
+                                   stbir_edge edge_mode_horizontal, stbir_edge edge_mode_vertical, 
+                                   stbir_filter filter_horizontal,  stbir_filter filter_vertical,
+                                   stbir_colorspace space, void *alloc_context,
+                                   float s0, float t0, float s1, float t1)
+{
+    return stbir__resize_arbitrary(alloc_context, input_pixels, input_w, input_h, input_stride_in_bytes,
+        output_pixels, output_w, output_h, output_stride_in_bytes,
+        s0,t0,s1,t1,NULL,num_channels,alpha_channel,flags, datatype, filter_horizontal, filter_vertical,
+        edge_mode_horizontal, edge_mode_vertical, space);
+}
+
+#endif // STB_IMAGE_RESIZE_IMPLEMENTATION

stb_textedit.h

@@ -1,4 +1,4 @@
-// stb_textedit.h - v1.4  - public domain - Sean Barrett
+// stb_textedit.h - v1.5  - public domain - Sean Barrett
 // Development of this library was sponsored by RAD Game Tools
 //
 // This C header file implements the guts of a multi-line text-editing
@@ -30,6 +30,7 @@
 //
 // VERSION HISTORY
 //
+//   1.5  (2014-09-10) add support for secondary keys for OS X
 //   1.4  (2014-08-17) fix signed/unsigned warnings
 //   1.3  (2014-06-19) fix mouse clicking to round to nearest char boundary
 //   1.2  (2014-05-27) fix some RAD types that had crept into the new code
@@ -43,6 +44,7 @@
 //
 //   Ulf Winklemann: move-by-word in 1.1
 //   Scott Graham: mouse selection bugfix in 1.3
+//   Fabian Giesen: secondary key inputs in 1.5
 //
 // USAGE
 //
@@ -142,6 +144,10 @@
 //                                 required for WORDLEFT/WORDRIGHT
 //    STB_TEXTEDIT_K_WORDLEFT    keyboard input to move cursor left one word // e.g. ctrl-LEFT
 //    STB_TEXTEDIT_K_WORDRIGHT   keyboard input to move cursor right one word // e.g. ctrl-RIGHT
+//    STB_TEXTEDIT_K_LINESTART2  secondary keyboard input to move cursor to start of line
+//    STB_TEXTEDIT_K_LINEEND2    secondary keyboard input to move cursor to end of line
+//    STB_TEXTEDIT_K_TEXTSTART2  secondary keyboard input to move cursor to start of text
+//    STB_TEXTEDIT_K_TEXTEND2    secondary keyboard input to move cursor to end of text
 //
 // Todo:
 //    STB_TEXTEDIT_K_PGUP        keyboard input to move cursor up a page
@@ -917,23 +923,35 @@ retry:
          state->has_preferred_x = 0;
          break;
          
+#ifdef STB_TEXTEDIT_K_TEXTSTART2
+      case STB_TEXTEDIT_K_TEXTSTART2:
+#endif
       case STB_TEXTEDIT_K_TEXTSTART:
          state->cursor = state->select_start = state->select_end = 0;
          state->has_preferred_x = 0;
          break;
 
+#ifdef STB_TEXTEDIT_K_TEXTEND2
+      case STB_TEXTEDIT_K_TEXTEND2:
+#endif
       case STB_TEXTEDIT_K_TEXTEND:
          state->cursor = STB_TEXTEDIT_STRINGLEN(str);
          state->select_start = state->select_end = 0;
          state->has_preferred_x = 0;
          break;
         
+#ifdef STB_TEXTEDIT_K_TEXTSTART2
+      case STB_TEXTEDIT_K_TEXTSTART2 | STB_TEXTEDIT_K_SHIFT:
+#endif
       case STB_TEXTEDIT_K_TEXTSTART | STB_TEXTEDIT_K_SHIFT:
          stb_textedit_prep_selection_at_cursor(state);
          state->cursor = state->select_end = 0;
          state->has_preferred_x = 0;
          break;
 
+#ifdef STB_TEXTEDIT_K_TEXTEND2
+      case STB_TEXTEDIT_K_TEXTEND2 | STB_TEXTEDIT_K_SHIFT:
+#endif
       case STB_TEXTEDIT_K_TEXTEND | STB_TEXTEDIT_K_SHIFT:
          stb_textedit_prep_selection_at_cursor(state);
          state->cursor = state->select_end = STB_TEXTEDIT_STRINGLEN(str);
@@ -941,6 +959,9 @@ retry:
          break;
 
 
+#ifdef STB_TEXTEDIT_K_LINESTART2
+      case STB_TEXTEDIT_K_LINESTART2:
+#endif
       case STB_TEXTEDIT_K_LINESTART: {
          StbFindState find;
          stb_textedit_clamp(str, state);
@@ -951,6 +972,9 @@ retry:
          break;
       }
 
+#ifdef STB_TEXTEDIT_K_LINEEND2
+      case STB_TEXTEDIT_K_LINEEND2:
+#endif
       case STB_TEXTEDIT_K_LINEEND: {
          StbFindState find;
          stb_textedit_clamp(str, state);
@@ -961,6 +985,9 @@ retry:
          break;
       }
 
+#ifdef STB_TEXTEDIT_K_LINESTART2
+      case STB_TEXTEDIT_K_LINESTART2 | STB_TEXTEDIT_K_SHIFT:
+#endif
       case STB_TEXTEDIT_K_LINESTART | STB_TEXTEDIT_K_SHIFT: {
          StbFindState find;
          stb_textedit_clamp(str, state);
@@ -971,6 +998,9 @@ retry:
          break;
       }
 
+#ifdef STB_TEXTEDIT_K_LINEEND2
+      case STB_TEXTEDIT_K_LINEEND2 | STB_TEXTEDIT_K_SHIFT:
+#endif
       case STB_TEXTEDIT_K_LINEEND | STB_TEXTEDIT_K_SHIFT: {
          StbFindState find;
          stb_textedit_clamp(str, state);

tests/resample_test.cpp

@@ -0,0 +1,983 @@
+#include <malloc.h>
+
+#if defined(_WIN32) && _MSC_VER > 1200
+#define STBIR_ASSERT(x) \
+	if (!(x)) {         \
+		__debugbreak();  \
+	} else
+#else
+#include <assert.h>
+#define STBIR_ASSERT(x) assert(x)
+#endif
+
+#define STBIR_MALLOC stbir_malloc
+#define STBIR_FREE stbir_free
+
+class stbir_context {
+public:
+	stbir_context()
+	{
+		size = 1000000;
+		memory = malloc(size);
+	}
+
+	~stbir_context()
+	{
+		free(memory);
+	}
+
+	size_t size;
+	void* memory;
+} g_context;
+
+void* stbir_malloc(size_t size, void* context)
+{
+	if (!context)
+		return malloc(size);
+
+	stbir_context* real_context = (stbir_context*)context;
+	if (size > real_context->size)
+		return 0;
+
+	return real_context->memory;
+}
+
+void stbir_free(void* memory, void* context)
+{
+	if (!context)
+		free(memory);
+}
+
+//#include <stdio.h>
+void stbir_progress(float p)
+{
+	//printf("%f\n", p);
+	STBIR_ASSERT(p >= 0 && p <= 1);
+}
+
+#define STBIR_PROGRESS_REPORT stbir_progress
+
+#define STB_IMAGE_RESIZE_IMPLEMENTATION
+#define STB_IMAGE_RESIZE_STATIC
+#include "stb_image_resize.h"
+
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include "stb_image_write.h"
+
+#define STB_IMAGE_IMPLEMENTATION
+#include "stb_image.h"
+
+#ifdef _WIN32
+#include <sys/timeb.h>
+#endif
+
+#include <direct.h>
+
+#define MT_SIZE 624
+static size_t g_aiMT[MT_SIZE];
+static size_t g_iMTI = 0;
+
+// Mersenne Twister implementation from Wikipedia.
+// Avoiding use of the system rand() to be sure that our tests generate the same test data on any system.
+void mtsrand(size_t iSeed)
+{
+	g_aiMT[0] = iSeed;
+	for (size_t i = 1; i < MT_SIZE; i++)
+	{
+		size_t inner1 = g_aiMT[i - 1];
+		size_t inner2 = (g_aiMT[i - 1] >> 30);
+		size_t inner = inner1 ^ inner2;
+		g_aiMT[i] = (0x6c078965 * inner) + i;
+	}
+
+	g_iMTI = 0;
+}
+
+size_t mtrand()
+{
+	if (g_iMTI == 0)
+	{
+		for (size_t i = 0; i < MT_SIZE; i++)
+		{
+			size_t y = (0x80000000 & (g_aiMT[i])) + (0x7fffffff & (g_aiMT[(i + 1) % MT_SIZE]));
+			g_aiMT[i] = g_aiMT[(i + 397) % MT_SIZE] ^ (y >> 1);
+			if ((y % 2) == 1)
+				g_aiMT[i] = g_aiMT[i] ^ 0x9908b0df;
+		}
+	}
+
+	size_t y = g_aiMT[g_iMTI];
+	y = y ^ (y >> 11);
+	y = y ^ ((y << 7) & (0x9d2c5680));
+	y = y ^ ((y << 15) & (0xefc60000));
+	y = y ^ (y >> 18);
+
+	g_iMTI = (g_iMTI + 1) % MT_SIZE;
+
+	return y;
+}
+
+
+inline float mtfrand()
+{
+	const int ninenine = 999999;
+	return (float)(mtrand() % ninenine)/ninenine;
+}
+
+static void resizer(int argc, char **argv)
+{
+	unsigned char* input_pixels;
+	unsigned char* output_pixels;
+	int w, h;
+	int n;
+	int out_w, out_h;
+	input_pixels = stbi_load(argv[1], &w, &h, &n, 0);
+	out_w = w*3;
+	out_h = h*3;
+	output_pixels = (unsigned char*) malloc(out_w*out_h*n);
+	//stbir_resize_uint8_srgb(input_pixels, w, h, 0, output_pixels, out_w, out_h, 0, n, -1,0);
+	stbir_resize_uint8(input_pixels, w, h, 0, output_pixels, out_w, out_h, 0, n);
+	stbi_write_png("output.png", out_w, out_h, n, output_pixels, 0);
+	exit(0);
+}
+
+static void performance(int argc, char **argv)
+{
+	unsigned char* input_pixels;
+	unsigned char* output_pixels;
+	int w, h, count;
+	int n, i;
+	int out_w, out_h, srgb=1;
+	input_pixels = stbi_load(argv[1], &w, &h, &n, 0);
+    #if 0
+    out_w = w/4; out_h = h/4; count=100; // 1
+    #elif 0
+	out_w = w*2; out_h = h/4; count=20; // 2   // note this is structured pessimily, would be much faster to downsample vertically first
+    #elif 0
+    out_w = w/4; out_h = h*2; count=50; // 3
+    #elif 0
+    out_w = w*3; out_h = h*3; count=2; srgb=0; // 4
+    #else
+    out_w = w*3; out_h = h*3; count=2; // 5   // this is dominated by linear->sRGB conversion
+    #endif
+
+	output_pixels = (unsigned char*) malloc(out_w*out_h*n);
+    for (i=0; i < count; ++i)
+        if (srgb)
+	        stbir_resize_uint8_srgb(input_pixels, w, h, 0, output_pixels, out_w, out_h, 0, n,-1,0);
+        else
+	        stbir_resize(input_pixels, w, h, 0, output_pixels, out_w, out_h, 0, STBIR_TYPE_UINT8, n,-1, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_DEFAULT, STBIR_FILTER_DEFAULT, STBIR_COLORSPACE_LINEAR, NULL);
+	exit(0);
+}
+
+void test_suite(int argc, char **argv);
+
+int main(int argc, char** argv)
+{
+	//resizer(argc, argv);
+    //performance(argc, argv);
+
+	test_suite(argc, argv);
+	return 0;
+}
+
+void resize_image(const char* filename, float width_percent, float height_percent, stbir_filter filter, stbir_edge edge, stbir_colorspace colorspace, const char* output_filename)
+{
+	int w, h, n;
+
+	unsigned char* input_data = stbi_load(filename, &w, &h, &n, 0);
+	if (!input_data)
+	{
+		printf("Input image could not be loaded\n");
+		return;
+	}
+
+	int out_w = (int)(w * width_percent);
+	int out_h = (int)(h * height_percent);
+
+	unsigned char* output_data = (unsigned char*)malloc(out_w * out_h * n);
+
+	stbir_resize(input_data, w, h, 0, output_data, out_w, out_h, 0, STBIR_TYPE_UINT8, n, STBIR_ALPHA_CHANNEL_NONE, 0, edge, edge, filter, filter, colorspace, &g_context);
+
+	stbi_image_free(input_data);
+
+	stbi_write_png(output_filename, out_w, out_h, n, output_data, 0);
+
+	free(output_data);
+}
+
+template <typename F, typename T>
+void convert_image(const F* input, T* output, int length)
+{
+	double f = (pow(2.0, 8.0 * sizeof(T)) - 1) / (pow(2.0, 8.0 * sizeof(F)) - 1);
+	for (int i = 0; i < length; i++)
+		output[i] = (T)(((double)input[i]) * f);
+}
+
+template <typename T>
+void test_format(const char* file, float width_percent, float height_percent, stbir_datatype type, stbir_colorspace colorspace)
+{
+	int w, h, n;
+	unsigned char* input_data = stbi_load(file, &w, &h, &n, 0);
+
+	if (input_data == NULL)
+		return;
+
+
+	int new_w = (int)(w * width_percent);
+	int new_h = (int)(h * height_percent);
+
+	T* T_data = (T*)malloc(w * h * n * sizeof(T));
+    memset(T_data, 0, w*h*n*sizeof(T));
+	convert_image<unsigned char, T>(input_data, T_data, w * h * n);
+
+	T* output_data = (T*)malloc(new_w * new_h * n * sizeof(T));
+
+	stbir_resize(T_data, w, h, 0, output_data, new_w, new_h, 0, type, n, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_CATMULLROM, STBIR_FILTER_CATMULLROM, colorspace, &g_context);
+
+	free(T_data);
+	stbi_image_free(input_data);
+
+	unsigned char* char_data = (unsigned char*)malloc(new_w * new_h * n * sizeof(char));
+	convert_image<T, unsigned char>(output_data, char_data, new_w * new_h * n);
+
+	char output[200];
+	sprintf(output, "test-output/type-%d-%d-%d-%d-%s", type, colorspace, new_w, new_h, file);
+	stbi_write_png(output, new_w, new_h, n, char_data, 0);
+
+	free(char_data);
+	free(output_data);
+}
+
+void convert_image_float(const unsigned char* input, float* output, int length)
+{
+	for (int i = 0; i < length; i++)
+		output[i] = ((float)input[i])/255;
+}
+
+void convert_image_float(const float* input, unsigned char* output, int length)
+{
+	for (int i = 0; i < length; i++)
+		output[i] = (unsigned char)(stbir__saturate(input[i]) * 255);
+}
+
+void test_float(const char* file, float width_percent, float height_percent, stbir_datatype type, stbir_colorspace colorspace)
+{
+	int w, h, n;
+	unsigned char* input_data = stbi_load(file, &w, &h, &n, 0);
+
+	if (input_data == NULL)
+		return;
+
+	int new_w = (int)(w * width_percent);
+	int new_h = (int)(h * height_percent);
+
+	float* T_data = (float*)malloc(w * h * n * sizeof(float));
+	convert_image_float(input_data, T_data, w * h * n);
+
+	float* output_data = (float*)malloc(new_w * new_h * n * sizeof(float));
+
+	stbir_resize_float_generic(T_data, w, h, 0, output_data, new_w, new_h, 0, n, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_FILTER_CATMULLROM, colorspace, &g_context);
+
+	free(T_data);
+	stbi_image_free(input_data);
+
+	unsigned char* char_data = (unsigned char*)malloc(new_w * new_h * n * sizeof(char));
+	convert_image_float(output_data, char_data, new_w * new_h * n);
+
+	char output[200];
+	sprintf(output, "test-output/type-%d-%d-%d-%d-%s", type, colorspace, new_w, new_h, file);
+	stbi_write_png(output, new_w, new_h, n, char_data, 0);
+
+	free(char_data);
+	free(output_data);
+}
+
+void test_channels(const char* file, float width_percent, float height_percent, int channels)
+{
+	int w, h, n;
+	unsigned char* input_data = stbi_load(file, &w, &h, &n, 0);
+
+	if (input_data == NULL)
+		return;
+
+	int new_w = (int)(w * width_percent);
+	int new_h = (int)(h * height_percent);
+
+	unsigned char* channels_data = (unsigned char*)malloc(w * h * channels * sizeof(unsigned char));
+
+	for (int i = 0; i < w * h; i++)
+	{
+		int input_position = i * n;
+		int output_position = i * channels;
+
+		for (int c = 0; c < channels; c++)
+			channels_data[output_position + c] = input_data[input_position + stbir__min(c, n)];
+	}
+
+	unsigned char* output_data = (unsigned char*)malloc(new_w * new_h * channels * sizeof(unsigned char));
+
+	stbir_resize_uint8_srgb(channels_data, w, h, 0, output_data, new_w, new_h, 0, channels, STBIR_ALPHA_CHANNEL_NONE, 0);
+
+	free(channels_data);
+	stbi_image_free(input_data);
+
+	char output[200];
+	sprintf(output, "test-output/channels-%d-%d-%d-%s", channels, new_w, new_h, file);
+	stbi_write_png(output, new_w, new_h, channels, output_data, 0);
+
+	free(output_data);
+}
+
+void test_subpixel(const char* file, float width_percent, float height_percent, float s1, float t1)
+{
+	int w, h, n;
+	unsigned char* input_data = stbi_load(file, &w, &h, &n, 0);
+
+	if (input_data == NULL)
+		return;
+
+	s1 = ((float)w - 1 + s1)/w;
+	t1 = ((float)h - 1 + t1)/h;
+
+	int new_w = (int)(w * width_percent);
+	int new_h = (int)(h * height_percent);
+
+	unsigned char* output_data = (unsigned char*)malloc(new_w * new_h * n * sizeof(unsigned char));
+
+	stbir_resize_region(input_data, w, h, 0, output_data, new_w, new_h, 0, STBIR_TYPE_UINT8, n, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_BOX, STBIR_FILTER_CATMULLROM, STBIR_COLORSPACE_SRGB, &g_context, 0, 0, s1, t1);
+
+	stbi_image_free(input_data);
+
+	char output[200];
+	sprintf(output, "test-output/subpixel-%d-%d-%f-%f-%s", new_w, new_h, s1, t1, file);
+	stbi_write_png(output, new_w, new_h, n, output_data, 0);
+
+	free(output_data);
+}
+
+unsigned int* pixel(unsigned int* buffer, int x, int y, int c, int w, int n)
+{
+	return &buffer[y*w*n + x*n + c];
+}
+
+void test_premul()
+{
+	unsigned int input[2 * 2 * 4];
+	unsigned int output[1 * 1 * 4];
+	unsigned int output2[2 * 2 * 4];
+
+	memset(input, 0, sizeof(input));
+
+	// First a test to make sure premul is working properly.
+
+	// Top left - solid red
+	*pixel(input, 0, 0, 0, 2, 4) = 255;
+	*pixel(input, 0, 0, 3, 2, 4) = 255;
+
+	// Bottom left - solid red
+	*pixel(input, 0, 1, 0, 2, 4) = 255;
+	*pixel(input, 0, 1, 3, 2, 4) = 255;
+
+	// Top right - transparent green
+	*pixel(input, 1, 0, 1, 2, 4) = 255;
+	*pixel(input, 1, 0, 3, 2, 4) = 25;
+
+	// Bottom right - transparent green
+	*pixel(input, 1, 1, 1, 2, 4) = 255;
+	*pixel(input, 1, 1, 3, 2, 4) = 25;
+
+	stbir_resize(input, 2, 2, 0, output, 1, 1, 0, STBIR_TYPE_UINT32, 4, 3, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_BOX, STBIR_FILTER_BOX, STBIR_COLORSPACE_LINEAR, &g_context);
+
+	float r = (float)255 / 4294967296;
+	float g = (float)255 / 4294967296;
+	float ra = (float)255 / 4294967296;
+	float ga = (float)25 / 4294967296;
+	float a = (ra + ga) / 2;
+
+	STBIR_ASSERT(output[0] == (unsigned int)(r * ra / 2 / a * 4294967296 + 0.5f)); // 232
+	STBIR_ASSERT(output[1] == (unsigned int)(g * ga / 2 / a * 4294967296 + 0.5f)); // 23
+	STBIR_ASSERT(output[2] == 0);
+	STBIR_ASSERT(output[3] == (unsigned int)(a * 4294967296 + 0.5f)); // 140
+
+	// Now a test to make sure it doesn't clobber existing values.
+
+	// Top right - completely transparent green
+	*pixel(input, 1, 0, 1, 2, 4) = 255;
+	*pixel(input, 1, 0, 3, 2, 4) = 0;
+
+	// Bottom right - completely transparent green
+	*pixel(input, 1, 1, 1, 2, 4) = 255;
+	*pixel(input, 1, 1, 3, 2, 4) = 0;
+
+	stbir_resize(input, 2, 2, 0, output2, 2, 2, 0, STBIR_TYPE_UINT32, 4, 3, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_BOX, STBIR_FILTER_BOX, STBIR_COLORSPACE_LINEAR, &g_context);
+
+	STBIR_ASSERT(*pixel(output2, 0, 0, 0, 2, 4) == 255);
+	STBIR_ASSERT(*pixel(output2, 0, 0, 1, 2, 4) == 0);
+	STBIR_ASSERT(*pixel(output2, 0, 0, 2, 2, 4) == 0);
+	STBIR_ASSERT(*pixel(output2, 0, 0, 3, 2, 4) == 255);
+
+	STBIR_ASSERT(*pixel(output2, 0, 1, 0, 2, 4) == 255);
+	STBIR_ASSERT(*pixel(output2, 0, 1, 1, 2, 4) == 0);
+	STBIR_ASSERT(*pixel(output2, 0, 1, 2, 2, 4) == 0);
+	STBIR_ASSERT(*pixel(output2, 0, 1, 3, 2, 4) == 255);
+
+	STBIR_ASSERT(*pixel(output2, 1, 0, 0, 2, 4) == 0);
+	STBIR_ASSERT(*pixel(output2, 1, 0, 1, 2, 4) == 255);
+	STBIR_ASSERT(*pixel(output2, 1, 0, 2, 2, 4) == 0);
+	STBIR_ASSERT(*pixel(output2, 1, 0, 3, 2, 4) == 0);
+
+	STBIR_ASSERT(*pixel(output2, 1, 1, 0, 2, 4) == 0);
+	STBIR_ASSERT(*pixel(output2, 1, 1, 1, 2, 4) == 255);
+	STBIR_ASSERT(*pixel(output2, 1, 1, 2, 2, 4) == 0);
+	STBIR_ASSERT(*pixel(output2, 1, 1, 3, 2, 4) == 0);
+}
+
+// test that splitting a pow-2 image into tiles produces identical results
+void test_subpixel_1()
+{
+	unsigned char image[8 * 8];
+
+	mtsrand(0);
+
+	for (int i = 0; i < sizeof(image); i++)
+		image[i] = mtrand() & 255;
+
+	unsigned char output_data[16 * 16];
+
+	stbir_resize_region(image, 8, 8, 0, output_data, 16, 16, 0, STBIR_TYPE_UINT8, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_CATMULLROM, STBIR_FILTER_CATMULLROM, STBIR_COLORSPACE_SRGB, &g_context, 0, 0, 1, 1);
+
+	unsigned char output_left[8 * 16];
+	unsigned char output_right[8 * 16];
+
+	stbir_resize_region(image, 8, 8, 0, output_left, 8, 16, 0, STBIR_TYPE_UINT8, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_CATMULLROM, STBIR_FILTER_CATMULLROM, STBIR_COLORSPACE_SRGB, &g_context, 0, 0, 0.5f, 1);
+	stbir_resize_region(image, 8, 8, 0, output_right, 8, 16, 0, STBIR_TYPE_UINT8, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_CATMULLROM, STBIR_FILTER_CATMULLROM, STBIR_COLORSPACE_SRGB, &g_context, 0.5f, 0, 1, 1);
+
+	for (int x = 0; x < 8; x++)
+	{
+		for (int y = 0; y < 16; y++)
+		{
+			STBIR_ASSERT(output_data[y * 16 + x] == output_left[y * 8 + x]);
+			STBIR_ASSERT(output_data[y * 16 + x + 8] == output_right[y * 8 + x]);
+		}
+	}
+}
+
+// test that replicating an image and using a subtile of it produces same results as wraparound
+void test_subpixel_2()
+{
+	unsigned char image[8 * 8];
+
+	mtsrand(0);
+
+	for (int i = 0; i < sizeof(image); i++)
+		image[i] = mtrand() & 255;
+
+	unsigned char large_image[32 * 32];
+
+	for (int x = 0; x < 8; x++)
+	{
+		for (int y = 0; y < 8; y++)
+		{
+			for (int i = 0; i < 4; i++)
+			{
+				for (int j = 0; j < 4; j++)
+					large_image[j*4*8*8 + i*8 + y*4*8 + x] = image[y*8 + x];
+			}
+		}
+	}
+
+	unsigned char output_data_1[16 * 16];
+	unsigned char output_data_2[16 * 16];
+
+	stbir_resize(image, 8, 8, 0, output_data_1, 16, 16, 0, STBIR_TYPE_UINT8, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_WRAP, STBIR_EDGE_WRAP, STBIR_FILTER_CATMULLROM, STBIR_FILTER_CATMULLROM, STBIR_COLORSPACE_SRGB, &g_context);
+	stbir_resize_region(large_image, 32, 32, 0, output_data_2, 16, 16, 0, STBIR_TYPE_UINT8, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_WRAP, STBIR_EDGE_WRAP, STBIR_FILTER_CATMULLROM, STBIR_FILTER_CATMULLROM, STBIR_COLORSPACE_SRGB, &g_context, 0.25f, 0.25f, 0.5f, 0.5f);
+
+	{for (int x = 0; x < 16; x++)
+	{
+		for (int y = 0; y < 16; y++)
+			STBIR_ASSERT(output_data_1[y * 16 + x] == output_data_2[y * 16 + x]);
+	}}
+}
+
+// test that 0,0,1,1 subpixel produces same result as no-rect
+void test_subpixel_3()
+{
+	unsigned char image[8 * 8];
+
+	mtsrand(0);
+
+	for (int i = 0; i < sizeof(image); i++)
+		image[i] = mtrand() & 255;
+
+	unsigned char output_data_1[32 * 32];
+	unsigned char output_data_2[32 * 32];
+
+	stbir_resize_region(image, 8, 8, 0, output_data_1, 32, 32, 0, STBIR_TYPE_UINT8, 1, 0, STBIR_ALPHA_CHANNEL_NONE, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_CATMULLROM, STBIR_FILTER_CATMULLROM, STBIR_COLORSPACE_LINEAR, NULL, 0, 0, 1, 1);
+	stbir_resize_uint8(image, 8, 8, 0, output_data_2, 32, 32, 0, 1);
+
+	for (int x = 0; x < 32; x++)
+	{
+		for (int y = 0; y < 32; y++)
+			STBIR_ASSERT(output_data_1[y * 32 + x] == output_data_2[y * 32 + x]);
+	}
+}
+
+// test that 1:1 resample using s,t=0,0,1,1 with bilinear produces original image
+void test_subpixel_4()
+{
+	unsigned char image[8 * 8];
+
+	mtsrand(0);
+
+	for (int i = 0; i < sizeof(image); i++)
+		image[i] = mtrand() & 255;
+
+	unsigned char output[8 * 8];
+
+	stbir_resize_region(image, 8, 8, 0, output, 8, 8, 0, STBIR_TYPE_UINT8, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_TRIANGLE, STBIR_FILTER_TRIANGLE, STBIR_COLORSPACE_LINEAR, &g_context, 0, 0, 1, 1);
+	STBIR_ASSERT(memcmp(image, output, 8 * 8) == 0);
+}
+
+static unsigned int  image88_int[8][8];
+static unsigned char image88 [8][8];
+static unsigned char output88[8][8];
+static unsigned char output44[4][4];
+static unsigned char output22[2][2];
+static unsigned char output11[1][1];
+
+void resample_88(stbir_filter filter)
+{
+	stbir_resize_uint8_generic(image88[0],8,8,0, output88[0],8,8,0, 1,-1,0, STBIR_EDGE_CLAMP, filter, STBIR_COLORSPACE_LINEAR, NULL);
+	stbir_resize_uint8_generic(image88[0],8,8,0, output44[0],4,4,0, 1,-1,0, STBIR_EDGE_CLAMP, filter, STBIR_COLORSPACE_LINEAR, NULL);
+	stbir_resize_uint8_generic(image88[0],8,8,0, output22[0],2,2,0, 1,-1,0, STBIR_EDGE_CLAMP, filter, STBIR_COLORSPACE_LINEAR, NULL);
+	stbir_resize_uint8_generic(image88[0],8,8,0, output11[0],1,1,0, 1,-1,0, STBIR_EDGE_CLAMP, filter, STBIR_COLORSPACE_LINEAR, NULL);
+}
+
+void verify_box(void)
+{
+	int i,j,t;
+
+	resample_88(STBIR_FILTER_BOX);
+
+	for (i=0; i < sizeof(image88); ++i)
+		STBIR_ASSERT(image88[0][i] == output88[0][i]);
+
+	t = 0;
+	for (j=0; j < 4; ++j)
+		for (i=0; i < 4; ++i) {
+			int n = image88[j*2+0][i*2+0]
+			      + image88[j*2+0][i*2+1]
+				  + image88[j*2+1][i*2+0]
+				  + image88[j*2+1][i*2+1];
+			STBIR_ASSERT(output44[j][i] == ((n+2)>>2) || output44[j][i] == ((n+1)>>2)); // can't guarantee exact rounding due to numerical precision
+			t += n;
+		}
+	STBIR_ASSERT(output11[0][0] == ((t+32)>>6) || output11[0][0] == ((t+31)>>6)); // can't guarantee exact rounding due to numerical precision
+}
+
+void verify_filter_normalized(stbir_filter filter, int output_size, unsigned int value)
+{
+	int i, j;
+	unsigned int output[64];
+
+	stbir_resize(image88_int[0], 8, 8, 0, output, output_size, output_size, 0, STBIR_TYPE_UINT32, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, filter, filter, STBIR_COLORSPACE_LINEAR, NULL);
+
+	for (j = 0; j < output_size; ++j)
+		for (i = 0; i < output_size; ++i)
+			STBIR_ASSERT(value == output[j*output_size + i]);
+}
+
+float round2(float f)
+{
+	return (float) floor(f+0.5f); // round() isn't C standard pre-C99
+}
+
+void test_filters(void)
+{
+	int i,j;
+
+	mtsrand(0);
+
+	for (i=0; i < sizeof(image88); ++i)
+		image88[0][i] = mtrand() & 255;
+	verify_box();
+
+	for (i=0; i < sizeof(image88); ++i)
+		image88[0][i] = 0;
+	image88[4][4] = 255;
+	verify_box();
+
+	for (j=0; j < 8; ++j)
+		for (i=0; i < 8; ++i)
+			image88[j][i] = (j^i)&1 ? 255 : 0;
+	verify_box();
+
+	for (j=0; j < 8; ++j)
+		for (i=0; i < 8; ++i)
+			image88[j][i] = i&2 ? 255 : 0;
+	verify_box();
+
+	int value = 64;
+
+	for (j = 0; j < 8; ++j)
+		for (i = 0; i < 8; ++i)
+			image88_int[j][i] = value;
+
+	verify_filter_normalized(STBIR_FILTER_BOX, 8, value);
+	verify_filter_normalized(STBIR_FILTER_TRIANGLE, 8, value);
+	verify_filter_normalized(STBIR_FILTER_CUBICBSPLINE, 8, value);
+	verify_filter_normalized(STBIR_FILTER_CATMULLROM, 8, value);
+	verify_filter_normalized(STBIR_FILTER_MITCHELL, 8, value);
+
+	verify_filter_normalized(STBIR_FILTER_BOX, 4, value);
+	verify_filter_normalized(STBIR_FILTER_TRIANGLE, 4, value);
+	verify_filter_normalized(STBIR_FILTER_CUBICBSPLINE, 4, value);
+	verify_filter_normalized(STBIR_FILTER_CATMULLROM, 4, value);
+	verify_filter_normalized(STBIR_FILTER_MITCHELL, 4, value);
+
+	verify_filter_normalized(STBIR_FILTER_BOX, 2, value);
+	verify_filter_normalized(STBIR_FILTER_TRIANGLE, 2, value);
+	verify_filter_normalized(STBIR_FILTER_CUBICBSPLINE, 2, value);
+	verify_filter_normalized(STBIR_FILTER_CATMULLROM, 2, value);
+	verify_filter_normalized(STBIR_FILTER_MITCHELL, 2, value);
+
+	verify_filter_normalized(STBIR_FILTER_BOX, 1, value);
+	verify_filter_normalized(STBIR_FILTER_TRIANGLE, 1, value);
+	verify_filter_normalized(STBIR_FILTER_CUBICBSPLINE, 1, value);
+	verify_filter_normalized(STBIR_FILTER_CATMULLROM, 1, value);
+	verify_filter_normalized(STBIR_FILTER_MITCHELL, 1, value);
+
+	{
+		// This test is designed to produce coefficients that are very badly denormalized.
+		unsigned int v = 556;
+
+		unsigned int input[100 * 100];
+		unsigned int output[11 * 11];
+
+		for (j = 0; j < 100 * 100; ++j)
+			input[j] = v;
+
+		stbir_resize(input, 100, 100, 0, output, 11, 11, 0, STBIR_TYPE_UINT32, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_TRIANGLE, STBIR_FILTER_TRIANGLE, STBIR_COLORSPACE_LINEAR, NULL);
+
+		for (j = 0; j < 11 * 11; ++j)
+			STBIR_ASSERT(v == output[j]);
+	}
+
+	{
+		// Now test the trapezoid filter for downsampling.
+		unsigned int input[3 * 1];
+		unsigned int output[2 * 1];
+
+		input[0] = 0;
+		input[1] = 255;
+		input[2] = 127;
+
+		stbir_resize(input, 3, 1, 0, output, 2, 1, 0, STBIR_TYPE_UINT32, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_BOX, STBIR_FILTER_BOX, STBIR_COLORSPACE_LINEAR, NULL);
+
+		STBIR_ASSERT(output[0] == (unsigned int)round2((float)(input[0] * 2 + input[1]) / 3));
+		STBIR_ASSERT(output[1] == (unsigned int)round2((float)(input[2] * 2 + input[1]) / 3));
+
+		stbir_resize(input, 1, 3, 0, output, 1, 2, 0, STBIR_TYPE_UINT32, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_BOX, STBIR_FILTER_BOX, STBIR_COLORSPACE_LINEAR, NULL);
+
+		STBIR_ASSERT(output[0] == (unsigned int)round2((float)(input[0] * 2 + input[1]) / 3));
+		STBIR_ASSERT(output[1] == (unsigned int)round2((float)(input[2] * 2 + input[1]) / 3));
+	}
+
+	{
+		// Now test the trapezoid filter for upsampling.
+		unsigned int input[2 * 1];
+		unsigned int output[3 * 1];
+
+		input[0] = 0;
+		input[1] = 255;
+
+		stbir_resize(input, 2, 1, 0, output, 3, 1, 0, STBIR_TYPE_UINT32, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_BOX, STBIR_FILTER_BOX, STBIR_COLORSPACE_LINEAR, NULL);
+
+		STBIR_ASSERT(output[0] == input[0]);
+		STBIR_ASSERT(output[1] == (input[0] + input[1]) / 2);
+		STBIR_ASSERT(output[2] == input[1]);
+
+		stbir_resize(input, 1, 2, 0, output, 1, 3, 0, STBIR_TYPE_UINT32, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_BOX, STBIR_FILTER_BOX, STBIR_COLORSPACE_LINEAR, NULL);
+
+		STBIR_ASSERT(output[0] == input[0]);
+		STBIR_ASSERT(output[1] == (input[0] + input[1]) / 2);
+		STBIR_ASSERT(output[2] == input[1]);
+	}
+
+	// checkerboard
+	{
+		unsigned char input[64][64];
+		unsigned char output[16][16];
+		int i,j;
+		for (j=0; j < 64; ++j)
+			for (i=0; i < 64; ++i)
+				input[j][i] = (i^j)&1 ? 255 : 0;
+		stbir_resize_uint8_generic(input[0], 64, 64, 0, output[0],16,16,0, 1,-1,0,STBIR_EDGE_WRAP,STBIR_FILTER_DEFAULT,STBIR_COLORSPACE_LINEAR,0);
+		for (j=0; j < 16; ++j)
+			for (i=0; i < 16; ++i)
+				STBIR_ASSERT(output[j][i] == 128);
+		stbir_resize_uint8_srgb_edgemode(input[0], 64, 64, 0, output[0],16,16,0, 1,-1,0,STBIR_EDGE_WRAP);
+		for (j=0; j < 16; ++j)
+			for (i=0; i < 16; ++i)
+				STBIR_ASSERT(output[j][i] == 188);
+
+
+	}
+
+	{
+		// Test trapezoid box filter
+		unsigned char input[2 * 1];
+		unsigned char output[127 * 1];
+
+		input[0] = 0;
+		input[1] = 255;
+
+		stbir_resize(input, 2, 1, 0, output, 127, 1, 0, STBIR_TYPE_UINT8, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_BOX, STBIR_FILTER_BOX, STBIR_COLORSPACE_LINEAR, NULL);
+		STBIR_ASSERT(output[0] == 0);
+		STBIR_ASSERT(output[127 / 2 - 1] == 0);
+		STBIR_ASSERT(output[127 / 2] == 128);
+		STBIR_ASSERT(output[127 / 2 + 1] == 255);
+		STBIR_ASSERT(output[126] == 255);
+		stbi_write_png("test-output/trapezoid-upsample-horizontal.png", 127, 1, 1, output, 0);
+
+		stbir_resize(input, 1, 2, 0, output, 1, 127, 0, STBIR_TYPE_UINT8, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_BOX, STBIR_FILTER_BOX, STBIR_COLORSPACE_LINEAR, NULL);
+		STBIR_ASSERT(output[0] == 0);
+		STBIR_ASSERT(output[127 / 2 - 1] == 0);
+		STBIR_ASSERT(output[127 / 2] == 128);
+		STBIR_ASSERT(output[127 / 2 + 1] == 255);
+		STBIR_ASSERT(output[126] == 255);
+		stbi_write_png("test-output/trapezoid-upsample-vertical.png", 1, 127, 1, output, 0);
+	}
+}
+
+#define UMAX32   4294967295U
+
+static void write32(char *filename, stbir_uint32 *output, int w, int h)
+{
+    stbir_uint8 *data = (stbir_uint8*) malloc(w*h*3);
+    for (int i=0; i < w*h*3; ++i)
+        data[i] = output[i]>>24;
+    stbi_write_png(filename, w, h, 3, data, 0);
+    free(data);
+}
+
+static void test_32(void)
+{
+    int w=100,h=120,x,y, out_w,out_h;
+    stbir_uint32 *input  = (stbir_uint32*) malloc(4 * 3 * w * h);
+    stbir_uint32 *output = (stbir_uint32*) malloc(4 * 3 * 3*w * 3*h);
+    for (y=0; y < h; ++y) {
+        for (x=0; x < w; ++x) {
+            input[y*3*w + x*3 + 0] = x * ( UMAX32/w );
+            input[y*3*w + x*3 + 1] = y * ( UMAX32/h );
+            input[y*3*w + x*3 + 2] = UMAX32/2;
+        }
+    }
+    out_w = w*33/16;
+    out_h = h*33/16;
+    stbir_resize(input,w,h,0,output,out_w,out_h,0,STBIR_TYPE_UINT32,3,-1,0,STBIR_EDGE_CLAMP,STBIR_EDGE_CLAMP,STBIR_FILTER_DEFAULT,STBIR_FILTER_DEFAULT,STBIR_COLORSPACE_LINEAR,NULL);
+    write32("test-output/seantest_1.png", output,out_w,out_h);
+
+    out_w = w*16/33;
+    out_h = h*16/33;
+    stbir_resize(input,w,h,0,output,out_w,out_h,0,STBIR_TYPE_UINT32,3,-1,0,STBIR_EDGE_CLAMP,STBIR_EDGE_CLAMP,STBIR_FILTER_DEFAULT,STBIR_FILTER_DEFAULT,STBIR_COLORSPACE_LINEAR,NULL);
+    write32("test-output/seantest_2.png", output,out_w,out_h);
+}
+
+
+void test_suite(int argc, char **argv)
+{
+	int i;
+	char *barbara;
+
+	_mkdir("test-output");
+
+	if (argc > 1)
+		barbara = argv[1];
+	else
+		barbara = "barbara.png";
+
+	// check what cases we need normalization for
+#if 1
+	{
+		float x, y;
+		for (x = -1; x < 1; x += 0.05f) {
+			float sums[5] = { 0 };
+			float o;
+			for (o = -5; o <= 5; ++o) {
+				sums[0] += stbir__filter_mitchell(x + o, 1);
+				sums[1] += stbir__filter_catmullrom(x + o, 1);
+				sums[2] += stbir__filter_cubic(x + o, 1);
+				sums[3] += stbir__filter_triangle(x + o, 1);
+				sums[4] += stbir__filter_trapezoid(x + o, 0.5f);
+			}
+			for (i = 0; i < 5; ++i)
+				STBIR_ASSERT(sums[i] >= 1.0 - 0.001 && sums[i] <= 1.0 + 0.001);
+		}
+
+#if 1	
+		for (y = 0.11f; y < 1; y += 0.01f) {  // Step
+			for (x = -1; x < 1; x += 0.05f) { // Phase
+				float sums[5] = { 0 };
+				float o;
+				for (o = -5; o <= 5; o += y) {
+					sums[0] += y * stbir__filter_mitchell(x + o, 1);
+					sums[1] += y * stbir__filter_catmullrom(x + o, 1);
+					sums[2] += y * stbir__filter_cubic(x + o, 1);
+					sums[4] += y * stbir__filter_trapezoid(x + o, 0.5f);
+					sums[3] += y * stbir__filter_triangle(x + o, 1);
+				}
+				for (i = 0; i < 3; ++i)
+					STBIR_ASSERT(sums[i] >= 1.0 - 0.0170 && sums[i] <= 1.0 + 0.0170);
+			}
+		}
+#endif
+	}
+#endif
+
+#if 0 // linear_to_srgb_uchar table
+	for (i=0; i < 256; ++i) {
+		float f = stbir__srgb_to_linear((i-0.5f)/255.0f);
+		printf("%9d, ", (int) ((f) * (1<<28)));
+		if ((i & 7) == 7)
+			printf("\n");
+	}
+#endif
+
+	// old tests that hacky fix worked on - test that
+	// every uint8 maps to itself
+	for (i = 0; i < 256; i++) {
+		float f = stbir__srgb_to_linear(float(i) / 255);
+		int n = stbir__linear_to_srgb_uchar(f);
+		STBIR_ASSERT(n == i);
+	}
+
+	// new tests that hacky fix failed for - test that
+	// values adjacent to uint8 round to nearest uint8
+	for (i = 0; i < 256; i++) {
+		for (float y = -0.42f; y <= 0.42f; y += 0.01f) {
+			float f = stbir__srgb_to_linear((i+y) / 255.0f);
+			int n = stbir__linear_to_srgb_uchar(f);
+			STBIR_ASSERT(n == i);
+		}
+	}
+
+	test_filters();
+
+	test_subpixel_1();
+	test_subpixel_2();
+	test_subpixel_3();
+	test_subpixel_4();
+
+	test_premul();
+
+	test_32();
+
+	// Some tests to make sure errors don't pop up with strange filter/dimension combinations.
+	stbir_resize(image88, 8, 8, 0, output88, 4, 16, 0, STBIR_TYPE_UINT8, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_BOX, STBIR_FILTER_CATMULLROM, STBIR_COLORSPACE_SRGB, &g_context);
+	stbir_resize(image88, 8, 8, 0, output88, 4, 16, 0, STBIR_TYPE_UINT8, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_CATMULLROM, STBIR_FILTER_BOX, STBIR_COLORSPACE_SRGB, &g_context);
+	stbir_resize(image88, 8, 8, 0, output88, 16, 4, 0, STBIR_TYPE_UINT8, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_BOX, STBIR_FILTER_CATMULLROM, STBIR_COLORSPACE_SRGB, &g_context);
+	stbir_resize(image88, 8, 8, 0, output88, 16, 4, 0, STBIR_TYPE_UINT8, 1, STBIR_ALPHA_CHANNEL_NONE, 0, STBIR_EDGE_CLAMP, STBIR_EDGE_CLAMP, STBIR_FILTER_CATMULLROM, STBIR_FILTER_BOX, STBIR_COLORSPACE_SRGB, &g_context);
+
+	for (i = 0; i < 10; i++)
+		test_subpixel(barbara, 0.5f, 0.5f, (float)i / 10, 1);
+
+	for (i = 0; i < 10; i++)
+		test_subpixel(barbara, 0.5f, 0.5f, 1, (float)i / 10);
+
+	for (i = 0; i < 10; i++)
+		test_subpixel(barbara, 2, 2, (float)i / 10, 1);
+
+	for (i = 0; i < 10; i++)
+		test_subpixel(barbara, 2, 2, 1, (float)i / 10);
+
+	// Channels test
+	test_channels(barbara, 0.5f, 0.5f, 1);
+	test_channels(barbara, 0.5f, 0.5f, 2);
+	test_channels(barbara, 0.5f, 0.5f, 3);
+	test_channels(barbara, 0.5f, 0.5f, 4);
+
+	test_channels(barbara, 2, 2, 1);
+	test_channels(barbara, 2, 2, 2);
+	test_channels(barbara, 2, 2, 3);
+	test_channels(barbara, 2, 2, 4);
+
+	// filter tests
+	resize_image(barbara, 2, 2, STBIR_FILTER_BOX         , STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, "test-output/barbara-upsample-nearest.png");
+	resize_image(barbara, 2, 2, STBIR_FILTER_TRIANGLE    , STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, "test-output/barbara-upsample-bilinear.png");
+	resize_image(barbara, 2, 2, STBIR_FILTER_CUBICBSPLINE, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, "test-output/barbara-upsample-bicubic.png");
+	resize_image(barbara, 2, 2, STBIR_FILTER_CATMULLROM  , STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, "test-output/barbara-upsample-catmullrom.png");
+	resize_image(barbara, 2, 2, STBIR_FILTER_MITCHELL    , STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, "test-output/barbara-upsample-mitchell.png");
+
+	resize_image(barbara, 0.5f, 0.5f, STBIR_FILTER_BOX         , STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, "test-output/barbara-downsample-nearest.png");
+	resize_image(barbara, 0.5f, 0.5f, STBIR_FILTER_TRIANGLE    , STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, "test-output/barbara-downsample-bilinear.png");
+	resize_image(barbara, 0.5f, 0.5f, STBIR_FILTER_CUBICBSPLINE, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, "test-output/barbara-downsample-bicubic.png");
+	resize_image(barbara, 0.5f, 0.5f, STBIR_FILTER_CATMULLROM  , STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, "test-output/barbara-downsample-catmullrom.png");
+	resize_image(barbara, 0.5f, 0.5f, STBIR_FILTER_MITCHELL    , STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, "test-output/barbara-downsample-mitchell.png");
+
+	for (i = 10; i < 100; i++)
+	{
+		char outname[200];
+		sprintf(outname, "test-output/barbara-width-%d.jpg", i);
+		resize_image(barbara, (float)i / 100, 1, STBIR_FILTER_CATMULLROM, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, outname);
+	}
+
+	for (i = 110; i < 500; i += 10)
+	{
+		char outname[200];
+		sprintf(outname, "test-output/barbara-width-%d.jpg", i);
+		resize_image(barbara, (float)i / 100, 1, STBIR_FILTER_CATMULLROM, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, outname);
+	}
+
+	for (i = 10; i < 100; i++)
+	{
+		char outname[200];
+		sprintf(outname, "test-output/barbara-height-%d.jpg", i);
+		resize_image(barbara, 1, (float)i / 100, STBIR_FILTER_CATMULLROM, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, outname);
+	}
+
+	for (i = 110; i < 500; i += 10)
+	{
+		char outname[200];
+		sprintf(outname, "test-output/barbara-height-%d.jpg", i);
+		resize_image(barbara, 1, (float)i / 100, STBIR_FILTER_CATMULLROM, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, outname);
+	}
+
+	for (i = 50; i < 200; i += 10)
+	{
+		char outname[200];
+		sprintf(outname, "test-output/barbara-width-height-%d.jpg", i);
+		resize_image(barbara, 100 / (float)i, (float)i / 100, STBIR_FILTER_CATMULLROM, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_SRGB, outname);
+	}
+
+	test_format<unsigned short>(barbara, 0.5, 2.0, STBIR_TYPE_UINT16, STBIR_COLORSPACE_SRGB);
+	test_format<unsigned short>(barbara, 0.5, 2.0, STBIR_TYPE_UINT16, STBIR_COLORSPACE_LINEAR);
+	test_format<unsigned short>(barbara, 2.0, 0.5, STBIR_TYPE_UINT16, STBIR_COLORSPACE_SRGB);
+	test_format<unsigned short>(barbara, 2.0, 0.5, STBIR_TYPE_UINT16, STBIR_COLORSPACE_LINEAR);
+
+	test_format<unsigned int>(barbara, 0.5, 2.0, STBIR_TYPE_UINT32, STBIR_COLORSPACE_SRGB);
+	test_format<unsigned int>(barbara, 0.5, 2.0, STBIR_TYPE_UINT32, STBIR_COLORSPACE_LINEAR);
+	test_format<unsigned int>(barbara, 2.0, 0.5, STBIR_TYPE_UINT32, STBIR_COLORSPACE_SRGB);
+	test_format<unsigned int>(barbara, 2.0, 0.5, STBIR_TYPE_UINT32, STBIR_COLORSPACE_LINEAR);
+
+	test_float(barbara, 0.5, 2.0, STBIR_TYPE_FLOAT, STBIR_COLORSPACE_SRGB);
+	test_float(barbara, 0.5, 2.0, STBIR_TYPE_FLOAT, STBIR_COLORSPACE_LINEAR);
+	test_float(barbara, 2.0, 0.5, STBIR_TYPE_FLOAT, STBIR_COLORSPACE_SRGB);
+	test_float(barbara, 2.0, 0.5, STBIR_TYPE_FLOAT, STBIR_COLORSPACE_LINEAR);
+
+	// Edge behavior tests
+	resize_image("hgradient.png", 2, 2, STBIR_FILTER_CATMULLROM, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_LINEAR, "test-output/hgradient-clamp.png");
+	resize_image("hgradient.png", 2, 2, STBIR_FILTER_CATMULLROM, STBIR_EDGE_WRAP, STBIR_COLORSPACE_LINEAR, "test-output/hgradient-wrap.png");
+
+	resize_image("vgradient.png", 2, 2, STBIR_FILTER_CATMULLROM, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_LINEAR, "test-output/vgradient-clamp.png");
+	resize_image("vgradient.png", 2, 2, STBIR_FILTER_CATMULLROM, STBIR_EDGE_WRAP, STBIR_COLORSPACE_LINEAR, "test-output/vgradient-wrap.png");
+
+	resize_image("1px-border.png", 2, 2, STBIR_FILTER_CATMULLROM, STBIR_EDGE_REFLECT, STBIR_COLORSPACE_LINEAR, "test-output/1px-border-reflect.png");
+	resize_image("1px-border.png", 2, 2, STBIR_FILTER_CATMULLROM, STBIR_EDGE_CLAMP, STBIR_COLORSPACE_LINEAR, "test-output/1px-border-clamp.png");
+
+	// sRGB tests
+	resize_image("gamma_colors.jpg", .5f, .5f, STBIR_FILTER_CATMULLROM, STBIR_EDGE_REFLECT, STBIR_COLORSPACE_SRGB, "test-output/gamma_colors.jpg");
+	resize_image("gamma_2.2.jpg", .5f, .5f, STBIR_FILTER_CATMULLROM, STBIR_EDGE_REFLECT, STBIR_COLORSPACE_SRGB, "test-output/gamma_2.2.jpg");
+	resize_image("gamma_dalai_lama_gray.jpg", .5f, .5f, STBIR_FILTER_CATMULLROM, STBIR_EDGE_REFLECT, STBIR_COLORSPACE_SRGB, "test-output/gamma_dalai_lama_gray.jpg");
+}

tests/resample_test_c.c

@@ -0,0 +1,5 @@
+#define STB_IMAGE_RESIZE_IMPLEMENTATION
+#define STB_IMAGE_RESIZE_STATIC
+#include "stb_image_resize.h"
+
+// Just to make sure it will build properly with a c compiler

tests/resize.dsp

@@ -0,0 +1,93 @@
+# Microsoft Developer Studio Project File - Name="resize" - Package Owner=<4>
+# Microsoft Developer Studio Generated Build File, Format Version 6.00
+# ** DO NOT EDIT **
+
+# TARGTYPE "Win32 (x86) Console Application" 0x0103
+
+CFG=resize - Win32 Debug
+!MESSAGE This is not a valid makefile. To build this project using NMAKE,
+!MESSAGE use the Export Makefile command and run
+!MESSAGE 
+!MESSAGE NMAKE /f "resize.mak".
+!MESSAGE 
+!MESSAGE You can specify a configuration when running NMAKE
+!MESSAGE by defining the macro CFG on the command line. For example:
+!MESSAGE 
+!MESSAGE NMAKE /f "resize.mak" CFG="resize - Win32 Debug"
+!MESSAGE 
+!MESSAGE Possible choices for configuration are:
+!MESSAGE 
+!MESSAGE "resize - Win32 Release" (based on "Win32 (x86) Console Application")
+!MESSAGE "resize - Win32 Debug" (based on "Win32 (x86) Console Application")
+!MESSAGE 
+
+# Begin Project
+# PROP AllowPerConfigDependencies 0
+# PROP Scc_ProjName ""
+# PROP Scc_LocalPath ""
+CPP=cl.exe
+RSC=rc.exe
+
+!IF  "$(CFG)" == "resize - Win32 Release"
+
+# PROP BASE Use_MFC 0
+# PROP BASE Use_Debug_Libraries 0
+# PROP BASE Output_Dir "Release"
+# PROP BASE Intermediate_Dir "Release"
+# PROP BASE Target_Dir ""
+# PROP Use_MFC 0
+# PROP Use_Debug_Libraries 0
+# PROP Output_Dir "Release"
+# PROP Intermediate_Dir "Release"
+# PROP Ignore_Export_Lib 0
+# PROP Target_Dir ""
+# ADD BASE CPP /nologo /W3 /GX /O2 /D "WIN32" /D "NDEBUG" /D "_CONSOLE" /D "_MBCS" /YX /FD /c
+# ADD CPP /nologo /G6 /W3 /GX /Z7 /O2 /I ".." /D "WIN32" /D "NDEBUG" /D "_CONSOLE" /D "_MBCS" /YX /FD /c
+# ADD BASE RSC /l 0x409 /d "NDEBUG"
+# ADD RSC /l 0x409 /d "NDEBUG"
+BSC32=bscmake.exe
+# ADD BASE BSC32 /nologo
+# ADD BSC32 /nologo
+LINK32=link.exe
+# ADD BASE LINK32 kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /nologo /subsystem:console /machine:I386
+# ADD LINK32 kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /nologo /subsystem:console /debug /machine:I386
+
+!ELSEIF  "$(CFG)" == "resize - Win32 Debug"
+
+# PROP BASE Use_MFC 0
+# PROP BASE Use_Debug_Libraries 1
+# PROP BASE Output_Dir "Debug"
+# PROP BASE Intermediate_Dir "Debug"
+# PROP BASE Target_Dir ""
+# PROP Use_MFC 0
+# PROP Use_Debug_Libraries 1
+# PROP Output_Dir "Debug"
+# PROP Intermediate_Dir "Debug"
+# PROP Target_Dir ""
+# ADD BASE CPP /nologo /W3 /Gm /GX /ZI /Od /D "WIN32" /D "_DEBUG" /D "_CONSOLE" /D "_MBCS" /YX /FD /GZ /c
+# ADD CPP /nologo /W3 /Gm /GX /ZI /Od /I ".." /D "WIN32" /D "_DEBUG" /D "_CONSOLE" /D "_MBCS" /YX /FD /GZ /c
+# ADD BASE RSC /l 0x409 /d "_DEBUG"
+# ADD RSC /l 0x409 /d "_DEBUG"
+BSC32=bscmake.exe
+# ADD BASE BSC32 /nologo
+# ADD BSC32 /nologo
+LINK32=link.exe
+# ADD BASE LINK32 kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /nologo /subsystem:console /debug /machine:I386 /pdbtype:sept
+# ADD LINK32 kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /nologo /subsystem:console /debug /machine:I386 /pdbtype:sept
+
+!ENDIF 
+
+# Begin Target
+
+# Name "resize - Win32 Release"
+# Name "resize - Win32 Debug"
+# Begin Source File
+
+SOURCE=.\resample_test.cpp
+# End Source File
+# Begin Source File
+
+SOURCE=..\stb_image_resize.h
+# End Source File
+# End Target
+# End Project

tests/stb.dsp

@@ -106,10 +106,18 @@ SOURCE=..\stb_dxt.h
 # End Source File
 # Begin Source File
 
+SOURCE=..\stb_herringbone_wang_tile.h
+# End Source File
+# Begin Source File
+
 SOURCE=..\stb_image.h
 # End Source File
 # Begin Source File
 
+SOURCE=..\stb_image_resize.h
+# End Source File
+# Begin Source File
+
 SOURCE=..\stb_image_write.h
 # End Source File
 # Begin Source File

tests/stb.dsw

@@ -63,6 +63,18 @@ Package=<4>
 
 ###############################################################################
 
+Project: "resize"=.\resize\resize.dsp - Package Owner=<4>
+
+Package=<5>
+{{{
+}}}
+
+Package=<4>
+{{{
+}}}
+
+###############################################################################
+
 Project: "stb"=.\stb.dsp - Package Owner=<4>
 
 Package=<5>

tests/test_c_compilation.c

@@ -5,6 +5,7 @@
 #define STB_DIVIDE_IMPLEMENTATION
 #define STB_IMAGE_IMPLEMENTATION
 #define STB_HERRINGBONE_WANG_TILE_IMEPLEMENTATIOn
+#define STB_IMAGE_RESIZE_IMPLEMENTATION
 
 #include "stb_herringbone_wang_tile.h"
 #include "stb_image.h"
@@ -13,3 +14,4 @@
 #include "stb_dxt.h"
 #include "stb_c_lexer.h"
 #include "stb_divide.h"
+#include "stb_image_resize.h"

tools/README.list

@@ -1,12 +1,13 @@
-stb_vorbis.c      | audio    | decode ogg vorbis files from file/memory to float/16-bit signed output
-stb_image.h       | graphics | image loading/decoding from file/memory: JPG, PNG, TGA, BMP, PSD, GIF, HDR, PIC
-stb_truetype.h    | graphics | parse, decode, and rasterize characters from truetype fonts
-stb_image_write.h | graphics | image writing to disk: PNG, TGA, BMP
-stretchy_buffer.h | utility  | typesafe dynamic array for C (i.e. approximation to vector<>), doesn't compile as C++
-stb_textedit.h    | UI       | guts of a text editor for games etc implementing them from scratch
-stb_dxt.h         | 3D graphics | Fabian "ryg" Giesen's real-time DXT compressor
-stb_herringbone_wang_tile.h | games | herringbone Wang tile map generator
-stb_perlin.h      | 3D graphics | revised Perlin noise (3D input, 1D output)
-stb_c_lexer.h     | parsing  | simplify writing parsers for C-like languages
-stb_divide.h      | math     | more useful 32-bit modulus e.g. "euclidean divide"
-stb.h             | misc     | helper functions for C, mostly redundant in C++; basically author's personal stuff
+stb_vorbis.c                | audio       | decode ogg vorbis files from file/memory to float/16-bit signed output
+stb_image.h                 | graphics    | image loading/decoding from file/memory: JPG, PNG, TGA, BMP, PSD, GIF, HDR, PIC
+stb_truetype.h              | graphics    | parse, decode, and rasterize characters from truetype fonts
+stb_image_write.h           | graphics    | image writing to disk: PNG, TGA, BMP
+stb_image_resize.h          | graphics    | resize images larger/smaller with good quality
+stretchy_buffer.h           | utility     | typesafe dynamic array for C (i.e. approximation to vector<>), doesn't compile as C++
+stb_textedit.h              | UI          | guts of a text editor for games etc implementing them from scratch
+stb_dxt.h                   | 3D graphics | Fabian "ryg" Giesen's real-time DXT compressor
+stb_perlin.h                | 3D graphics | revised Perlin noise (3D input, 1D output)
+stb_herringbone_wang_tile.h | games       | herringbone Wang tile map generator
+stb_c_lexer.h               | parsing     | simplify writing parsers for C-like languages
+stb_divide.h                | math        | more useful 32-bit modulus e.g. "euclidean divide"
+stb.h                       | misc        | helper functions for C, mostly redundant in C++; basically author's personal stuff

tools/make_readme.dsp

@@ -84,5 +84,9 @@ LINK32=link.exe
 
 SOURCE=.\make_readme.c
 # End Source File
+# Begin Source File
+
+SOURCE=.\README.list
+# End Source File
 # End Target
 # End Project