CI tests for PNG, GZIP + ZLIB.

.github/workflows/ci.yml

@@ -75,6 +75,6 @@ jobs:
         shell: cmd
         run: |
           call "C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Auxiliary\Build\vcvars64.bat
-          cd core\image\tests
-          python3 download_assets.py
+          cd tests\core
+          call build.bat
         timeout-minutes: 10

core/image/tests/build.bat

@@ -1,2 +0,0 @@
-@echo off
-python3 download_assets.py

tests/core/build.bat

@@ -0,0 +1,4 @@
+@echo off
+python3 download_assets.py
+odin test image    -vet -strict-style
+odin test compress -vet -strict-style

tests/core/compress/test_core_compress.odin

@@ -0,0 +1,120 @@
+package test_core_compress
+
+/*
+	Copyright 2021 Jeroen van Rijn <[email protected]>.
+	Made available under Odin's BSD-3 license.
+
+	List of contributors:
+		Jeroen van Rijn: Initial implementation.
+
+	A test suite for ZLIB, GZIP and PNG.
+*/
+
+import "core:testing"
+
+import "core:compress/zlib"
+import "core:compress/gzip"
+
+import "core:bytes"
+import "core:fmt"
+
+import "core:mem"
+import "core:os"
+import "core:io"
+
+when ODIN_TEST {
+	expect  :: testing.expect
+} else {
+	expect  :: proc(t: ^testing.T, condition: bool, message: string) {
+		if !condition {
+			fmt.println(message)
+		}
+	}
+}
+
+main :: proc() {
+	w, _ := io.to_writer(os.stream_from_handle(os.stdout))
+	t := testing.T{w=w}
+	zlib_test(&t)
+	gzip_test(&t)
+}
+
+@test
+zlib_test :: proc(t: ^testing.T) {
+	ODIN_DEMO := []u8{
+		120, 156, 101, 144,  77, 110, 131,  48,  16, 133, 215, 204,  41, 158,  44,
+		 69,  73,  32, 148, 182,  75,  35,  14, 208, 125,  47,  96, 185, 195, 143,
+		130,  13,  50,  38,  81,  84, 101, 213,  75, 116, 215,  43, 246,   8,  53,
+		 82, 126,   8, 181, 188, 152, 153, 111, 222, 147, 159, 123, 165, 247, 170,
+		 98,  24, 213,  88, 162, 198, 244, 157, 243,  16, 186, 115,  44,  75, 227,
+		  5,  77, 115,  72, 137, 222, 117, 122, 179, 197,  39,  69, 161, 170, 156,
+		 50, 144,   5,  68, 130,   4,  49, 126, 127, 190, 191, 144,  34,  19,  57,
+		 69,  74, 235, 209, 140, 173, 242, 157, 155,  54, 158, 115, 162, 168,  12,
+		181, 239, 246, 108,  17, 188, 174, 242, 224,  20,  13, 199, 198, 235, 250,
+		194, 166, 129,  86,   3,  99, 157, 172,  37, 230,  62,  73, 129, 151, 252,
+		 70, 211,   5,  77,  31, 104, 188, 160, 113, 129, 215,  59, 205,  22,  52,
+		123, 160,  83, 142, 255, 242,  89, 123,  93, 149, 200,  50, 188,  85,  54,
+		252,  18, 248, 192, 238, 228, 235, 198,  86, 224, 118, 224, 176, 113, 166,
+		112,  67, 106, 227, 159, 122, 215,  88,  95, 110, 196, 123, 205, 183, 224,
+		 98,  53,   8, 104, 213, 234, 201, 147,   7, 248, 192,  14, 170,  29,  25,
+		171,  15,  18,  59, 138, 112,  63,  23, 205, 110, 254, 136, 109,  78, 231,
+		 63, 234, 138, 133, 204,
+	}
+
+	buf: bytes.Buffer
+
+	track: mem.Tracking_Allocator
+	mem.tracking_allocator_init(&track, context.allocator)
+	context.allocator = mem.tracking_allocator(&track)
+
+	err  := zlib.inflate(ODIN_DEMO, &buf)
+
+	expect(t, err == nil, "ZLIB failed to decompress ODIN_DEMO")
+	s := bytes.buffer_to_string(&buf)
+
+	expect(t, s[68] == 240 && s[69] == 159 && s[70] == 152, "ZLIB result should've contained 😃 at position 68.")
+
+	expect(t, len(s) == 438, "ZLIB result has an unexpected length.")
+
+	bytes.buffer_destroy(&buf)
+
+	for _, v in track.allocation_map {
+		error := fmt.tprintf("ZLIB test leaked %v bytes", v.size)
+		expect(t, false, error)
+	}
+}
+
+@test
+gzip_test :: proc(t: ^testing.T) {
+	// Small GZIP file with fextra, fname and fcomment present.
+	TEST: []u8 = {
+		0x1f, 0x8b, 0x08, 0x1c, 0xcb, 0x3b, 0x3a, 0x5a,
+		0x02, 0x03, 0x07, 0x00, 0x61, 0x62, 0x03, 0x00,
+		0x63, 0x64, 0x65, 0x66, 0x69, 0x6c, 0x65, 0x6e,
+		0x61, 0x6d, 0x65, 0x00, 0x54, 0x68, 0x69, 0x73,
+		0x20, 0x69, 0x73, 0x20, 0x61, 0x20, 0x63, 0x6f,
+		0x6d, 0x6d, 0x65, 0x6e, 0x74, 0x00, 0x2b, 0x48,
+		0xac, 0xcc, 0xc9, 0x4f, 0x4c, 0x01, 0x00, 0x15,
+		0x6a, 0x2c, 0x42, 0x07, 0x00, 0x00, 0x00,
+	}
+
+	buf: bytes.Buffer
+
+	track: mem.Tracking_Allocator
+	mem.tracking_allocator_init(&track, context.allocator)
+	context.allocator = mem.tracking_allocator(&track)
+
+	err := gzip.load(TEST, &buf) // , 438);
+
+	expect(t, err == nil, "GZIP failed to decompress TEST")
+	s := bytes.buffer_to_string(&buf)
+
+	expect(t, s == "payload", "GZIP result wasn't 'payload'")
+
+	bytes.buffer_destroy(&buf)
+
+	for _, v in track.allocation_map {
+		error := fmt.tprintf("GZIP test leaked %v bytes", v.size)
+		expect(t, false, error)
+	}
+}

tests/core/image/test_core_image.odin

@@ -0,0 +1,1922 @@
+package test_core_image
+
+/*
+	Copyright 2021 Jeroen van Rijn <[email protected]>.
+	Made available under Odin's BSD-3 license.
+
+	List of contributors:
+		Jeroen van Rijn: Initial implementation.
+
+	A test suite for ZLIB, GZIP and PNG.
+*/
+
+import "core:testing"
+
+import "core:compress"
+import "core:image"
+import "core:image/png"
+
+import "core:bytes"
+import "core:hash"
+import "core:fmt"
+
+import "core:mem"
+import "core:os"
+import "core:time"
+
+import "core:runtime"
+import "core:io"
+
+WRITE_PPM_ON_FAIL :: #config(WRITE_PPM_ON_FAIL, false)
+TEST_SUITE_PATH   :: "assets/PNG"
+
+when ODIN_TEST {
+	expect  :: testing.expect
+} else {
+	expect  :: proc(t: ^testing.T, condition: bool, message: string) {
+		if !condition {
+			fmt.println(message)
+		}
+	}
+}
+I_Error :: image.Error
+
+main :: proc() {
+	w, _ := io.to_writer(os.stream_from_handle(os.stdout))
+	t := testing.T{w=w}
+	png_test(&t)
+}
+
+PNG_Test :: struct {
+	file:   string,
+	tests:  []struct {
+		options:        image.Options,
+		expected_error: compress.Error,
+		dims:           PNG_Dims,
+		hash:           u32,
+	},
+}
+
+Default              :: image.Options{}
+Alpha_Add            :: image.Options{.alpha_add_if_missing}
+Premul_Drop          :: image.Options{.alpha_premultiply, .alpha_drop_if_present}
+Just_Drop            :: image.Options{.alpha_drop_if_present}
+Blend_BG             :: image.Options{.blend_background}
+Blend_BG_Keep        :: image.Options{.blend_background, .alpha_add_if_missing}
+Return_Metadata      :: image.Options{.return_metadata}
+No_Channel_Expansion :: image.Options{.do_not_expand_channels, .return_metadata}
+
+PNG_Dims    :: struct {
+	width:     int,
+	height:    int,
+	channels:  int,
+	depth:     int,
+}
+
+Basic_PNG_Tests       := []PNG_Test{
+	/*
+		Basic format tests:
+			http://www.schaik.com/pngsuite/pngsuite_bas_png.html
+	*/
+
+	{
+		"basn0g01", // Black and white.
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_1d8b_1934},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_0da2_8714},
+		},
+	},
+	{
+		"basn0g02", // 2 bit (4 level) grayscale
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_cce2_e274},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_2e3f_e285},
+		},
+	},
+	{
+		"basn0g04", // 4 bit (16 level) grayscale
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_e6ed_c27d},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_8d0f_641b},
+		},
+	},
+	{
+		"basn0g08", // 8 bit (256 level) grayscale
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_7e0a_8ab4},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_c395_683c},
+		},
+	},
+	{
+		"basn0g16", // 16 bit (64k level) grayscale
+		{
+			{Default,     nil, {32, 32, 3, 16}, 0x_d6ae_7df7},
+			{Alpha_Add,   nil, {32, 32, 4, 16}, 0x_a9da_b1bf},
+		},
+	},
+	{
+		"basn2c08", // 3x8 bits rgb color
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_7855_b9bf},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_2fb5_4036},
+		},
+	},
+	{
+		"basn2c16", // 3x16 bits rgb color
+		{
+			{Default,     nil, {32, 32, 3, 16}, 0x_8ec6_de79},
+			{Alpha_Add,   nil, {32, 32, 4, 16}, 0x_0a7e_bae6},
+		},
+	},
+	{
+		"basn3p01", // 1 bit (2 color) paletted
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_31ec_284b},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_4d84_31a4},
+		},
+	},
+	{
+		"basn3p02", // 2 bit (4 color) paletted
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_279a_463a},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_e4db_b6bc},
+		},
+	},
+	{
+		"basn3p04", // 4 bit (16 color) paletted
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_3a9e_038e},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_671f_880f},
+		},
+	},
+	{
+		"basn3p08", // 8 bit (256 color) paletted
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_ff6e_2940},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_3952_8682},
+		},
+	},
+	{
+		"basn4a08", // 8 bit grayscale + 8 bit alpha-channel
+		{
+			{Default,     nil, {32, 32, 4,  8}, 0x_905d_5b60},
+			{Premul_Drop, nil, {32, 32, 3,  8}, 0x_8c36_b12c},
+		},
+	},
+	{
+		"basn4a16", // 16 bit grayscale + 16 bit alpha-channel
+		{
+			{Default,     nil, {32, 32, 4, 16}, 0x_3000_e35c},
+			{Premul_Drop, nil, {32, 32, 3, 16}, 0x_0276_254b},
+		},
+	},
+	{
+		"basn6a08", // 3x8 bits rgb color + 8 bit alpha-channel
+		{
+			{Default,     nil, {32, 32, 4,  8}, 0x_a74d_f32c},
+			{Premul_Drop, nil, {32, 32, 3,  8}, 0x_3a5b_8b1c},
+		},
+	},
+	{
+		"basn6a16", // 3x16 bits rgb color + 16 bit alpha-channel
+		{
+			{Default,     nil, {32, 32, 4, 16}, 0x_087b_e531},
+			{Premul_Drop, nil, {32, 32, 3, 16}, 0x_de9d_19fd},
+		},
+	},
+}
+
+Interlaced_PNG_Tests  := []PNG_Test{
+	/*
+		Interlaced format tests:
+			http://www.schaik.com/pngsuite/pngsuite_int_png.html
+
+		Note that these have the same hash values as the
+		non-interlaced versionss above. It would be a failure if
+		they didn't, but we need these tests to exercise Adam-7.
+
+	*/
+
+	{
+		"basi0g01", // Black and white.
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_1d8b_1934},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_0da2_8714},
+		},
+	},
+	{
+		"basi0g02", // 2 bit (4 level) grayscale
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_cce2_e274},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_2e3f_e285},
+		},
+	},
+	{
+		"basi0g04", // 4 bit (16 level) grayscale
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_e6ed_c27d},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_8d0f_641b},
+		},
+	},
+	{
+		"basi0g08", // 8 bit (256 level) grayscale
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_7e0a_8ab4},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_c395_683c},
+		},
+	},
+	{
+		"basi0g16", // 16 bit (64k level) grayscale
+		{
+			{Default,     nil, {32, 32, 3, 16}, 0x_d6ae_7df7},
+			{Alpha_Add,   nil, {32, 32, 4, 16}, 0x_a9da_b1bf},
+		},
+	},
+	{
+		"basi2c08", // 3x8 bits rgb color
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_7855_b9bf},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_2fb5_4036},
+		},
+	},
+	{
+		"basi2c16", // 3x16 bits rgb color
+		{
+			{Default,     nil, {32, 32, 3, 16}, 0x_8ec6_de79},
+			{Alpha_Add,   nil, {32, 32, 4, 16}, 0x_0a7e_bae6},
+		},
+	},
+	{
+		"basi3p01", // 1 bit (2 color) paletted
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_31ec_284b},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_4d84_31a4},
+		},
+	},
+	{
+		"basi3p02", // 2 bit (4 color) paletted
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_279a_463a},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_e4db_b6bc},
+		},
+	},
+	{
+		"basi3p04", // 4 bit (16 color) paletted
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_3a9e_038e},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_671f_880f},
+		},
+	},
+	{
+		"basi3p08", // 8 bit (256 color) paletted
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_ff6e_2940},
+			{Alpha_Add,   nil, {32, 32, 4,  8}, 0x_3952_8682},
+		},
+	},
+	{
+		"basi4a08", // 8 bit grayscale + 8 bit alpha-channel
+		{
+			{Default,     nil, {32, 32, 4,  8}, 0x_905d_5b60},
+			{Premul_Drop, nil, {32, 32, 3,  8}, 0x_8c36_b12c},
+		},
+	},
+	{
+		"basi4a16", // 16 bit grayscale + 16 bit alpha-channel
+		{
+			{Default,     nil, {32, 32, 4, 16}, 0x_3000_e35c},
+			{Premul_Drop, nil, {32, 32, 3, 16}, 0x_0276_254b},
+		},
+	},
+	{
+		"basi6a08", // 3x8 bits rgb color + 8 bit alpha-channel
+		{
+			{Default,     nil, {32, 32, 4,  8}, 0x_a74d_f32c},
+			{Premul_Drop, nil, {32, 32, 3,  8}, 0x_3a5b_8b1c},
+		},
+	},
+	{
+		"basi6a16", // 3x16 bits rgb color + 16 bit alpha-channel
+		{
+			{Default,     nil, {32, 32, 4, 16}, 0x_087b_e531},
+			{Premul_Drop, nil, {32, 32, 3, 16}, 0x_de9d_19fd},
+		},
+	},
+}
+
+Odd_Sized_PNG_Tests   := []PNG_Test{
+	/*
+"        PngSuite", // Odd sizes / PNG-files:
+			http://www.schaik.com/pngsuite/pngsuite_siz_png.html
+
+		This tests curious sizes with and without interlacing.
+	*/
+
+	{
+		"s01i3p01", // 1x1 paletted file, interlaced
+		{
+			{Default,     nil, { 1,  1, 3,  8}, 0x_d243_369f},
+		},
+	},
+	{
+		"s01n3p01", // 1x1 paletted file, no interlacing
+		{
+			{Default,     nil, { 1,  1, 3,  8}, 0x_d243_369f},
+		},
+	},
+	{
+		"s02i3p01", // 2x2 paletted file, interlaced
+		{
+			{Default,     nil, { 2,  2, 3,  8}, 0x_9e93_1d85},
+		},
+	},
+	{
+		"s02n3p01", // 2x2 paletted file, no interlacing
+		{
+			{Default,     nil, { 2,  2, 3,  8}, 0x_9e93_1d85},
+		},
+	},
+	{
+		"s03i3p01", // 3x3 paletted file, interlaced
+		{
+			{Default,     nil, { 3,  3, 3,  8}, 0x_6916_380e},
+		},
+	},
+	{
+		"s03n3p01", // 3x3 paletted file, no interlacing
+		{
+			{Default,     nil, { 3,  3, 3,  8}, 0x_6916_380e},
+		},
+	},
+	{
+		"s04i3p01", // 4x4 paletted file, interlaced
+		{
+			{Default,     nil, { 4,  4, 3,  8}, 0x_c2e0_d49b},
+		},
+	},
+	{
+		"s04n3p01", // 4x4 paletted file, no interlacing
+		{
+			{Default,     nil, { 4,  4, 3,  8}, 0x_c2e0_d49b},
+		},
+	},
+	{
+		"s05i3p02", // 5x5 paletted file, interlaced
+		{
+			{Default,     nil, { 5,  5, 3,  8}, 0x_1242_b6fb},
+		},
+	},
+	{
+		"s05n3p02", // 5x5 paletted file, no interlacing
+		{
+			{Default,     nil, { 5,  5, 3,  8}, 0x_1242_b6fb},
+		},
+	},
+	{
+		"s06i3p02", // 6x6 paletted file, interlaced
+		{
+			{Default,     nil, { 6,  6, 3,  8}, 0x_d758_9540},
+		},
+	},
+	{
+		"s06n3p02", // 6x6 paletted file, no interlacing
+		{
+			{Default,     nil, { 6,  6, 3,  8}, 0x_d758_9540},
+		},
+	},
+	{
+		"s07i3p02", // 7x7 paletted file, interlaced
+		{
+			{Default,     nil, { 7,  7, 3,  8}, 0x_d2cc_f489},
+		},
+	},
+	{
+		"s07n3p02", // 7x7 paletted file, no interlacing
+		{
+			{Default,     nil, { 7,  7, 3,  8}, 0x_d2cc_f489},
+		},
+	},
+	{
+		"s08i3p02", // 8x8 paletted file, interlaced
+		{
+			{Default,     nil, { 8,  8, 3,  8}, 0x_2ba1_b03e},
+		},
+	},
+	{
+		"s08n3p02", // 8x8 paletted file, no interlacing
+		{
+			{Default,     nil, { 8,  8, 3,  8}, 0x_2ba1_b03e},
+		},
+	},
+	{
+		"s09i3p02", // 9x9 paletted file, interlaced
+		{
+			{Default,     nil, { 9,  9, 3,  8}, 0x_9762_d2ed},
+		},
+	},
+	{
+		"s09n3p02", // 9x9 paletted file, no interlacing
+		{
+			{Default,     nil, { 9,  9, 3,  8}, 0x_9762_d2ed},
+		},
+	},
+	{
+		"s32i3p04", // 32x32 paletted file, interlaced
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_ad01_f44d},
+		},
+	},
+	{
+		"s32n3p04", // 32x32 paletted file, no interlacing
+		{
+			{Default,     nil, {32, 32, 3,  8}, 0x_ad01_f44d},
+		},
+	},
+	{
+		"s33i3p04", // 33x33 paletted file, interlaced
+		{
+			{Default,     nil, {33, 33, 3,  8}, 0x_d2f4_ae68},
+		},
+	},
+	{
+		"s33n3p04", // 33x33 paletted file, no interlacing
+		{
+			{Default,     nil, {33, 33, 3,  8}, 0x_d2f4_ae68},
+		},
+	},
+	{
+		"s34i3p04", // 34x34 paletted file, interlaced
+		{
+			{Default,     nil, {34, 34, 3,  8}, 0x_bbed_a3f7},
+		},
+	},
+	{
+		"s34n3p04", // 34x34 paletted file, no interlacing
+		{
+			{Default,     nil, {34, 34, 3,  8}, 0x_bbed_a3f7},
+		},
+	},
+	{
+		"s35i3p04", // 35x35 paletted file, interlaced
+		{
+			{Default,     nil, {35, 35, 3,  8}, 0x_9929_3acf},
+		},
+	},
+	{
+		"s35n3p04", // 35x35 paletted file, no interlacing
+		{
+			{Default,     nil, {35, 35, 3,  8}, 0x_9929_3acf},
+		},
+	},
+	{
+		"s36i3p04", // 36x36 paletted file, interlaced
+		{
+			{Default,     nil, {36, 36, 3,  8}, 0x_f51a_96e0},
+		},
+	},
+	{
+		"s36n3p04", // 36x36 paletted file, no interlacing
+		{
+			{Default,     nil, {36, 36, 3,  8}, 0x_f51a_96e0},
+		},
+	},
+	{
+		"s37i3p04", // 37x37 paletted file, interlaced
+		{
+			{Default,     nil, {37, 37, 3,  8}, 0x_9207_58a4},
+		},
+	},
+	{
+		"s37n3p04", // 37x37 paletted file, no interlacing
+		{
+			{Default,     nil, {37, 37, 3,  8}, 0x_9207_58a4},
+		},
+	},
+	{
+		"s38i3p04", // 38x38 paletted file, interlaced
+		{
+			{Default,     nil, {38, 38, 3,  8}, 0x_eb3b_f324},
+		},
+	},
+	{
+		"s38n3p04", // 38x38 paletted file, no interlacing
+		{
+			{Default,     nil, {38, 38, 3,  8}, 0x_eb3b_f324},
+		},
+	},
+	{
+		"s39i3p04", // 39x39 paletted file, interlaced
+		{
+			{Default,     nil, {39, 39, 3,  8}, 0x_c06d_7da1},
+		},
+	},
+	{
+		"s39n3p04", // 39x39 paletted file, no interlacing
+		{
+			{Default,     nil, {39, 39, 3,  8}, 0x_c06d_7da1},
+		},
+	},
+	{
+		"s40i3p04", // 40x40 paletted file, interlaced
+		{
+			{Default,     nil, {40, 40, 3,  8}, 0x_0d46_58a0},
+		},
+	},
+	{
+		"s40n3p04", // 40x40 paletted file, no interlacing
+		{
+			{Default,     nil, {40, 40, 3,  8}, 0x_0d46_58a0},
+		},
+	},
+}
+
+PNG_bKGD_Tests        := []PNG_Test{
+	/*
+"        PngSuite", // Background colors / PNG-files:
+			http://www.schaik.com/pngsuite/pngsuite_bck_png.html
+
+		This tests PNGs with and without a bKGD chunk and how we handle
+		blending the background.
+	*/
+
+	{
+		"bgai4a08", // 8 bit grayscale, alpha, no background chunk, interlaced
+		{
+			{Default,     nil, {32, 32, 4,  8}, 0x_905d_5b60},
+			// No background, therefore no background blending and 3 channels.
+			{Blend_BG,    nil, {32, 32, 4,  8}, 0x_905d_5b60},
+		},
+	},
+	{
+		"bgai4a16", // 16 bit grayscale, alpha, no background chunk, interlaced
+		{
+			{Default,     nil, {32, 32, 4, 16}, 0x_3000_e35c},
+			// No background, therefore no background blending and 3 channels.
+			{Blend_BG,    nil, {32, 32, 4, 16}, 0x_3000_e35c},
+		},
+	},
+	{
+		"bgan6a08", // 3x8 bits rgb color, alpha, no background chunk
+		{
+			{Default,     nil, {32, 32, 4,  8}, 0x_a74d_f32c},
+			// No background, therefore no background blending and 3 channels.
+			{Blend_BG,    nil, {32, 32, 4,  8}, 0x_a74d_f32c},
+		},
+	},
+	{
+		"bgan6a16", // 3x16 bits rgb color, alpha, no background chunk
+		{
+			{Default,     nil, {32, 32, 4, 16}, 0x_087b_e531},
+			// No background, therefore no background blending and 3 channels.
+			{Blend_BG,    nil, {32, 32, 4, 16}, 0x_087b_e531},
+		},
+	},
+	{
+		"bgbn4a08", // 8 bit grayscale, alpha, black background chunk
+		{
+			{Default,       nil, {32, 32, 4,  8}, 0x_905d_5b60},
+			{Blend_BG,      nil, {32, 32, 3,  8}, 0x_8c36_b12c},
+			/*
+				Blend with background but keep useless alpha channel now set to 255.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_d4a2_3649},
+		},
+	},
+	{
+		"bggn4a16", // 16 bit grayscale, alpha, gray background chunk
+		{
+			{Default,       nil, {32, 32, 4, 16}, 0x_3000_e35c},
+			{Blend_BG,      nil, {32, 32, 3, 16}, 0x_0b49_0dc1},
+			/*
+				Blend with background but keep useless alpha channel.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4, 16}, 0x_073f_eb13},
+		},
+	},
+	{
+		"bgwn6a08", // 3x8 bits rgb color, alpha, white background chunk
+		{
+			{Default,       nil, {32, 32, 4,  8}, 0x_a74d_f32c},
+			{Blend_BG,      nil, {32, 32, 3,  8}, 0x_b60d_d910},
+			/*
+				Blend with background but keep useless alpha channel.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_01ce_2ec6},
+		},
+	},
+	{
+		"bgyn6a16", // 3x16 bits rgb color, alpha, yellow background chunk
+		{
+			{Default,       nil, {32, 32, 4, 16}, 0x_087b_e531},
+			{Blend_BG,      nil, {32, 32, 3, 16}, 0x_1a16_7d87},
+			/*
+				Blend with background but keep useless alpha channel.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4, 16}, 0x_4d73_9955},
+		},
+	},
+}
+
+PNG_tRNS_Tests        := []PNG_Test{
+	/*
+		PngSuite - Transparency:
+			http://www.schaik.com/pngsuite/pngsuite_trn_png.html
+
+		This tests PNGs with and without a tRNS chunk and how we handle
+		keyed transparency.
+	*/
+
+	{
+		"tbbn0g04", // transparent, black background chunk
+		{
+			{Default,       nil, {32, 32, 4,  8}, 0x_5c8e_af83},
+			{Blend_BG,      nil, {32, 32, 3,  8}, 0x_9b95_ca37},
+			/*
+				Blend with background but keep useless alpha channel now set to 255.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_5ea6_fd32},
+		},
+	},
+	{
+		"tbbn2c16", // transparent, blue background chunk
+		{
+			{Default,       nil, {32, 32, 4, 16}, 0x_07fe_8090},
+			{Blend_BG,      nil, {32, 32, 3, 16}, 0x_5863_8fa2},
+			/*
+				Blend with background but keep useless alpha channel now set to 65535.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4, 16}, 0x_be56_b8fa},
+		},
+	},
+	{
+		"tbbn3p08", // transparent, black background chunk
+		{
+			{Default,       nil, {32, 32, 4,  8}, 0x_9d56_cd67},
+			{Blend_BG,      nil, {32, 32, 3,  8}, 0x_8071_0060},
+			/*
+				Blend with background but keep useless alpha channel now set to 255.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_c821_11f1},
+		},
+	},
+	{
+		"tbgn2c16", // transparent, green background chunk
+		{
+			{Default,       nil, {32, 32, 4, 16}, 0x_07fe_8090},
+			{Blend_BG,      nil, {32, 32, 3, 16}, 0x_70da_708a},
+			/*
+				Blend with background but keep useless alpha channel now set to 65535.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4, 16}, 0x_97b3_a190},
+		},
+	},
+	{
+		"tbbn3p08", // transparent, black background chunk
+		{
+			{Default,       nil, {32, 32, 4,  8}, 0x_9d56_cd67},
+			{Blend_BG,      nil, {32, 32, 3,  8}, 0x_8071_0060},
+			/*
+				Blend with background but keep useless alpha channel now set to 255.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_c821_11f1},
+		},
+	},
+	{
+		"tbgn3p08", // transparent, light-gray background chunk
+		{
+			{Default,       nil, {32, 32, 4,  8}, 0x_9d56_cd67},
+			{Blend_BG,      nil, {32, 32, 3,  8}, 0x_078b_74c4},
+			/*
+				Blend with background but keep useless alpha channel now set to 255.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_d103_068d},
+		},
+	},
+	{
+		"tbrn2c08", // transparent, red background chunk
+		{
+			{Default,       nil, {32, 32, 4,  8}, 0x_0370_ef89},
+			{Blend_BG,      nil, {32, 32, 3,  8}, 0x_6f68_a445},
+			/*
+				Blend with background but keep useless alpha channel now set to 255.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_2610_a9b7},
+		},
+	},
+	{
+		"tbwn0g16", // transparent, white background chunk
+		{
+			{Default,       nil, {32, 32, 4, 16}, 0x_5386_656a},
+			{Blend_BG,      nil, {32, 32, 3, 16}, 0x_6bdd_8c69},
+			/*
+				Blend with background but keep useless alpha channel now set to 65535.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4, 16}, 0x_1157_5f08},
+		},
+	},
+	{
+		"tbwn3p08", // transparent, white background chunk
+		{
+			{Default,       nil, {32, 32, 4,  8}, 0x_9d56_cd67},
+			{Blend_BG,      nil, {32, 32, 3,  8}, 0x_4476_4e96},
+			/*
+				Blend with background but keep useless alpha channel now set to 255.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_dd92_0d33},
+		},
+	},
+	{
+		"tbyn3p08", // transparent, yellow background chunk
+		{
+			{Default,       nil, {32, 32, 4,  8}, 0x_9d56_cd67},
+			{Blend_BG,      nil, {32, 32, 3,  8}, 0x_18b9_da39},
+			/*
+				Blend with background but keep useless alpha channel now set to 255.
+			*/
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_b1d4_5c1e},
+		},
+	},
+	{
+		"tp0n0g08", // not transparent for reference (logo on gray)
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_dfa9_515c},
+			{Blend_BG,      nil, {32, 32, 3,  8}, 0x_dfa9_515c},
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_5796_5874},
+		},
+	},
+	{
+		"tp0n2c08", // not transparent for reference (logo on gray)
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_b426_b350},
+			{Blend_BG,      nil, {32, 32, 3,  8}, 0x_b426_b350},
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_679d_24b4},
+		},
+	},
+	{
+		"tp0n3p08", // not transparent for reference (logo on gray)
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_1549_3236},
+			{Blend_BG,      nil, {32, 32, 3,  8}, 0x_1549_3236},
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_130a_a165},
+		},
+	},
+	{
+		"tp1n3p08", // transparent, but no background chunk
+		{
+			{Default,       nil, {32, 32, 4,  8}, 0x_9d56_cd67},
+			{Blend_BG,      nil, {32, 32, 4,  8}, 0x_9d56_cd67},
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_9d56_cd67},
+		},
+	},
+	{
+		"tm3n3p02", // multiple levels of transparency, 3 entries
+		{
+			{Default,       nil, {32, 32, 4,  8}, 0x_e7da_a7f5},
+			{Blend_BG,      nil, {32, 32, 4,  8}, 0x_e7da_a7f5},
+			{Blend_BG_Keep, nil, {32, 32, 4,  8}, 0x_e7da_a7f5},
+			{Just_Drop,     nil, {32, 32, 3,  8}, 0x_e7f1_a455},
+		},
+	},
+}
+
+PNG_Filter_Tests      := []PNG_Test{
+	/*
+		PngSuite - Image filtering:
+
+			http://www.schaik.com/pngsuite/pngsuite_fil_png.html
+
+		This tests PNGs filters.
+	*/
+
+	{
+		"f00n0g08", // grayscale, no interlacing, filter-type 0
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_3f6b_9bc5},
+		},
+	},
+	{
+		"f00n2c08", // color, no interlacing, filter-type 0
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_3f1d_66ad},
+		},
+
+	},
+	{
+		"f01n0g08", // grayscale, no interlacing, filter-type 1
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_0ff8_9d6c},
+		},
+
+	},
+	{
+		"f01n2c08", // color, no interlacing, filter-type 1
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_11c1_b27e},
+		},
+	},
+	{
+		"f02n0g08", // grayscale, no interlacing, filter-type 2
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_a86b_4c1d},
+		},
+	},
+	{
+		"f02n2c08", // color, no interlacing, filter-type 2
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_7f1c_a785},
+		},
+	},
+	{
+		"f03n0g08", // grayscale, no interlacing, filter-type 3
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_66de_99f1},
+		},
+	},
+	{
+		"f03n2c08", // color, no interlacing, filter-type 3
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_3164_5d89},
+		},
+	},
+	{
+		"f04n0g08", // grayscale, no interlacing, filter-type 4
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_f655_bb7d},
+		},
+	},
+	{
+		"f04n2c08", // color, no interlacing, filter-type 4
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_7705_6a6f},
+		},
+	},
+	{
+		"f99n0g04", // bit-depth 4, filter changing per scanline
+		{
+			{Default,       nil, {32, 32, 3,  8}, 0x_d302_6ad9},
+		},
+	},
+}
+
+PNG_Varied_IDAT_Tests := []PNG_Test{
+	/*
+		PngSuite - Chunk ordering:
+
+			http://www.schaik.com/pngsuite/pngsuite_ord_png.html
+
+		This tests IDAT chunks of varying sizes.
+	*/
+
+	{
+		"oi1n0g16", // grayscale mother image with 1 idat-chunk
+		{
+			{Default,       nil, {32, 32, 3, 16}, 0x_d6ae_7df7},
+		},
+	},
+	{
+		"oi1n2c16", // color mother image with 1 idat-chunk
+		{
+			{Default,       nil, {32, 32, 3, 16}, 0x_8ec6_de79},
+		},
+	},
+	{
+		"oi2n0g16", // grayscale image with 2 idat-chunks
+		{
+			{Default,       nil, {32, 32, 3, 16}, 0x_d6ae_7df7},
+		},
+	},
+	{
+		"oi2n2c16", // color image with 2 idat-chunks
+		{
+			{Default,       nil, {32, 32, 3, 16}, 0x_8ec6_de79},
+		},
+	},
+	{
+		"oi4n0g16", // grayscale image with 4 unequal sized idat-chunks
+		{
+			{Default,       nil, {32, 32, 3, 16}, 0x_d6ae_7df7},
+		},
+	},
+	{
+		"oi4n2c16", // color image with 4 unequal sized idat-chunks
+		{
+			{Default,       nil, {32, 32, 3, 16}, 0x_8ec6_de79},
+		},
+	},
+	{
+		"oi9n0g16", // grayscale image with all idat-chunks length one
+		{
+			{Default,       nil, {32, 32, 3, 16}, 0x_d6ae_7df7},
+		},
+	},
+	{
+		"oi9n2c16", // color image with all idat-chunks length one
+		{
+			{Default,       nil, {32, 32, 3, 16}, 0x_8ec6_de79},
+		},
+	},
+}
+
+PNG_ZLIB_Levels_Tests := []PNG_Test{
+	/*
+		PngSuite - Zlib compression:
+
+			http://www.schaik.com/pngsuite/pngsuite_zlb_png.html
+
+		This tests varying levels of ZLIB compression.
+	*/
+
+	{
+		"z00n2c08", // color, no interlacing, compression level 0 (none)
+		{
+			{Default,         nil, {32, 32, 3,  8}, 0x_f8f7_d651},
+		},
+	},
+	{
+		"z03n2c08", // color, no interlacing, compression level 3
+		{
+			{Default,         nil, {32, 32, 3,  8}, 0x_f8f7_d651},
+		},
+	},
+	{
+		"z06n2c08", // color, no interlacing, compression level 6 (default)
+		{
+			{Default,         nil, {32, 32, 3,  8}, 0x_f8f7_d651},
+		},
+	},
+	{
+		"z09n2c08", // color, no interlacing, compression level 9 (maximum)
+		{
+			{Default,         nil, {32, 32, 3,  8}, 0x_f8f7_d651},
+		},
+	},
+	{
+		"logo-slim", // Odin logo, uses `repl_bytes` repeats at an offset greater than 1.
+		{
+			{Default,         nil, {500, 260, 4, 8}, 0x_3e75_4e4e},
+		},
+	},
+}
+
+PNG_sPAL_Tests        := []PNG_Test{
+	/*
+		PngSuite - Additional palettes:
+
+			http://www.schaik.com/pngsuite/pngsuite_pal_png.html
+
+		This tests handling of sPAL chunks.
+	*/
+
+	{
+		"pp0n2c16", // six-cube palette-chunk in true-color image
+		{
+			{Return_Metadata, nil, {32, 32, 3, 16}, 0x_8ec6_de79},
+		},
+	},
+	{
+		"pp0n6a08", // six-cube palette-chunk in true-color+alpha image
+		{
+			{Return_Metadata, nil, {32, 32, 4,  8}, 0x_0ee0_5c61},
+		},
+	},
+	{
+		"ps1n0g08", // six-cube suggested palette (1 byte) in grayscale image
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_7e0a_8ab4},
+		},
+	},
+	{
+		"ps1n2c16", // six-cube suggested palette (1 byte) in true-color image
+		{
+			{Return_Metadata, nil, {32, 32, 3, 16}, 0x_8ec6_de79},
+		},
+	},
+	{
+		"ps2n0g08", // six-cube suggested palette (2 bytes) in grayscale image
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_7e0a_8ab4},
+		},
+	},
+	{
+		"ps2n2c16", // six-cube suggested palette (2 bytes) in true-color image
+		{
+			{Return_Metadata, nil, {32, 32, 3, 16}, 0x_8ec6_de79},
+		},
+	},
+}
+
+PNG_Ancillary_Tests   := []PNG_Test{
+	/*
+		PngSuite" - Ancillary chunks:
+
+			http://www.schaik.com/pngsuite/pngsuite_cnk_png.html
+
+		This tests various chunk helpers.
+	*/
+
+	{
+		"ccwn2c08", // chroma chunk w:0.3127,0.3290 r:0.64,0.33 g:0.30,0.60 b:0.15,0.06
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_61b6_9e8e},
+		},
+	},
+	{
+		"ccwn3p08", // chroma chunk w:0.3127,0.3290 r:0.64,0.33 g:0.30,0.60 b:0.15,0.06
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_2e1d_8ef1},
+		},
+	},
+	{
+		"cdfn2c08", // physical pixel dimensions, 8x32 flat pixels
+		{
+			{Return_Metadata, nil, { 8, 32, 3,  8}, 0x_99af_40a3},
+		},
+	},
+	{
+		"cdhn2c08", // physical pixel dimensions, 32x8 high pixels
+		{
+			{Return_Metadata, nil, {32,  8, 3,  8}, 0x_84a4_ef40},
+		},
+	},
+	{
+		"cdsn2c08", // physical pixel dimensions, 8x8 square pixels
+		{
+			{Return_Metadata, nil, { 8,  8, 3,  8}, 0x_82b2_6daf},
+		},
+	},
+	{
+		"cdun2c08", // physical pixel dimensions, 1000 pixels per 1 meter
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_ee50_e3ca},
+		},
+	},
+	{
+		"ch1n3p04", // histogram 15 colors
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_3a9e_038e},
+		},
+	},
+	{
+		"ch2n3p08", // histogram 256 colors
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_ff6e_2940},
+		},
+	},
+	{
+		"cm0n0g04", // modification time, 01-jan-2000 12:34:56
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_c6bd_1a35},
+		},
+	},
+	{
+		"cm7n0g04", // modification time, 01-jan-1970 00:00:00
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_c6bd_1a35},
+		},
+	},
+	{
+		"cm9n0g04", // modification time, 31-dec-1999 23:59:59
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_c6bd_1a35},
+		},
+	},
+	{
+		"cs3n2c16", // color, 13 significant bits
+		{
+			{Return_Metadata, nil, {32, 32, 3, 16}, 0x_7919_bec4},
+		},
+	},
+	{
+		"cs3n3p08", // paletted, 3 significant bits
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_c472_63e3},
+		},
+	},
+	{
+		"cs5n2c08", // color, 5 significant bits
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_1b16_d169},
+		},
+	},
+	{
+		"cs5n3p08", // paletted, 5 significant bits
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_1b16_d169},
+		},
+	},
+	{
+		"cs8n2c08", // color, 8 significant bits (reference)
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_7306_351c},
+		},
+	},
+	{
+		"cs8n3p08", // paletted, 8 significant bits (reference)
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_7306_351c},
+		},
+	},
+	{
+		"ct0n0g04", // no textual data
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_c6bd_1a35},
+		},
+	},
+	{
+		"ct1n0g04", // with textual data
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_c6bd_1a35},
+		},
+	},
+	{
+		"ctzn0g04", // with compressed textual data
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_c6bd_1a35},
+		},
+	},
+	{
+		"cten0g04", // international UTF-8, english
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_908f_d2b2},
+		},
+	},
+	{
+		"ctfn0g04", // international UTF-8, finnish
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_7f7a_43a7},
+		},
+	},
+	{
+		"ctgn0g04", // international UTF-8, greek
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_0ad1_d3d6},
+		},
+	},
+	{
+		"cthn0g04", // international UTF-8, hindi
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_c461_c896},
+		},
+	},
+	{
+		"ctjn0g04", // international UTF-8, japanese
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_5539_0861},
+		},
+	},
+	{
+		"exif2c08", // chunk with jpeg exif data
+		{
+			{Return_Metadata, nil, {32, 32, 3,  8}, 0x_1a50_22ef},
+		},
+	},
+}
+
+
+Corrupt_PNG_Tests   := []PNG_Test{
+	/*
+		PngSuite - Corrupted files / PNG-files:
+
+			http://www.schaik.com/pngsuite/pngsuite_xxx_png.html
+
+		This test ensures corrupted PNGs are rejected.
+	*/
+
+	{
+		"xs1n0g01", // signature byte 1 MSBit reset to zero
+		{
+			{Default, I_Error.Invalid_PNG_Signature, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xs2n0g01", // signature byte 2 is a 'Q'
+		{
+			{Default, I_Error.Invalid_PNG_Signature, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xs4n0g01", // signature byte 4 lowercase
+		{
+			{Default, I_Error.Invalid_PNG_Signature, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xs7n0g01", // 7th byte a space instead of control-Z
+		{
+			{Default, I_Error.Invalid_PNG_Signature, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xcrn0g04", // added cr bytes
+		{
+			{Default, I_Error.Invalid_PNG_Signature, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xlfn0g04", // added lf bytes
+		{
+			{Default, I_Error.Invalid_PNG_Signature, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xhdn0g08", // incorrect IHDR checksum
+		{
+			{Default, compress.General_Error.Checksum_Failed, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xc1n0g08", // color type 1
+		{
+			{Default, I_Error.Unknown_Color_Type, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xc9n2c08", // color type 9
+		{
+			{Default, I_Error.Unknown_Color_Type, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xd0n2c08", // bit-depth 0
+		{
+			{Default, I_Error.Invalid_Color_Bit_Depth_Combo, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xd3n2c08", // bit-depth 3
+		{
+			{Default, I_Error.Invalid_Color_Bit_Depth_Combo, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xd9n2c08", // bit-depth 99
+		{
+			{Default, I_Error.Invalid_Color_Bit_Depth_Combo, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xdtn0g01", // missing IDAT chunk
+		{
+			{Default, I_Error.IDAT_Missing, {}, 0x_0000_0000},
+		},
+	},
+	{
+		"xcsn0g01", // incorrect IDAT checksum
+		{
+			{Default, compress.General_Error.Checksum_Failed, {}, 0x_0000_0000},
+		},
+	},
+
+}
+
+No_Postprocesing_Tests := []PNG_Test{
+	/*
+		These are some custom tests where we skip expanding to RGB(A).
+	*/
+	{
+		"ps1n0g08", // six-cube suggested palette (1 byte) in grayscale image
+		{
+			{No_Channel_Expansion, nil, {32, 32, 1,  8}, 0x784b_4a4e},
+		},
+	},
+	{
+		"basn0g16", // 16 bit (64k level) grayscale
+		{
+			{No_Channel_Expansion, nil, {32, 32, 1, 16}, 0x_2ab1_5133},
+		},
+	},
+	{
+		"basn3p04", // 4 bit (16 color) paletted
+		{
+			{No_Channel_Expansion, nil, {32, 32, 1,  8}, 0x_280e_99f1},
+		},
+	},
+}
+
+
+
+Text_Title      :: "PngSuite"
+Text_Software   :: "Created on a NeXTstation color using \"pnmtopng\"."
+Text_Descrption :: "A compilation of a set of images created to test the\nvarious color-types of the PNG format. Included are\nblack&white, color, paletted, with alpha channel, with\ntransparency formats. All bit-depths allowed according\nto the spec are present."
+
+Expected_Text := map[string]map[string]png.Text {
+	// .tEXt
+	"ct1n0g04" = map[string]png.Text {
+		"Title"       = png.Text{
+			text=Text_Title,
+		},
+		"Software"    = png.Text{
+			text=Text_Software,
+		},
+		"Description" = png.Text{
+			text=Text_Descrption,
+		},
+	},
+	// .zTXt
+	"ctzn0g04" = map[string]png.Text {
+		"Title"       = png.Text{
+			text=Text_Title,
+		},
+		"Software"    = png.Text{
+			text=Text_Software,
+		},
+		"Description" = png.Text{
+			text=Text_Descrption,
+		},
+	},
+	// .iTXt - international UTF-8, english
+	"cten0g04" = map[string]png.Text {
+		"Title"       = png.Text{
+			keyword_localized="Title",
+			language="en",
+		},
+		"Software"    = png.Text{
+			keyword_localized="Software",
+			language="en",
+		},
+		"Description" = png.Text{
+			keyword_localized="Description",
+			language="en",
+		},
+	},
+	// .iTXt - international UTF-8, finnish
+	"ctfn0g04" = map[string]png.Text {
+		"Title"       = png.Text{
+			keyword_localized = "Otsikko",
+			language = "fi",
+			text ="PngSuite",
+		},
+		"Software"    = png.Text{
+			keyword_localized = "Ohjelmistot",
+			language = "fi",
+			text = "Luotu NeXTstation väriä \"pnmtopng\".",
+		},
+		"Description" = png.Text{
+			keyword_localized = "Kuvaus",
+			language = "fi",
+			text = "kokoelma joukon kuvia luotu testata eri väri-tyyppisiä PNG-muodossa. Mukana on mustavalkoinen, väri, paletted, alpha-kanava, avoimuuden muodossa. Kaikki bit-syvyydessä mukaan sallittua spec on ​​läsnä.",
+		},
+	},
+	// .iTXt - international UTF-8, greek
+	"ctgn0g04" = map[string]png.Text {
+		"Title"       = png.Text{
+			keyword_localized = "Τίτλος",
+			language = "el",
+			text ="PngSuite",
+		},
+		"Software"    = png.Text{
+			keyword_localized = "Λογισμικό",
+			language = "el",
+			text = "Δημιουργήθηκε σε ένα χρώμα NeXTstation χρησιμοποιώντας \"pnmtopng\".",
+		},
+		"Description" = png.Text{
+			keyword_localized = "Περιγραφή",
+			language = "el",
+			text = "Μια συλλογή από ένα σύνολο εικόνων που δημιουργήθηκαν για τη δοκιμή των διαφόρων χρωμάτων-τύπων του μορφή PNG. Περιλαμβάνονται οι ασπρόμαυρες, χρώμα, paletted, με άλφα κανάλι, με μορφές της διαφάνειας. Όλοι λίγο-βάθη επιτρέπεται σύμφωνα με το spec είναι παρόντες.",
+		},
+	},
+	// .iTXt - international UTF-8, hindi
+	"cthn0g04" = map[string]png.Text {
+		"Title"       = png.Text{
+			keyword_localized = "शीर्षक",
+			language = "hi",
+			text ="PngSuite",
+		},
+		"Software"    = png.Text{
+			keyword_localized = "सॉफ्टवेयर",
+			language = "hi",
+			text = "एक NeXTstation \"pnmtopng \'का उपयोग कर रंग पर बनाया गया.",
+		},
+		"Description" = png.Text{
+			keyword_localized = "विवरण",
+			language = "hi",
+			text = "करने के लिए PNG प्रारूप के विभिन्न रंग प्रकार परीक्षण बनाया छवियों का एक सेट का एक संकलन. शामिल काले और सफेद, रंग, पैलेटेड हैं, अल्फा चैनल के साथ पारदर्शिता स्वरूपों के साथ. सभी बिट गहराई कल्पना के अनुसार की अनुमति दी मौजूद हैं.",
+		},
+	},
+	// .iTXt - international UTF-8, japanese
+	"ctjn0g04" = map[string]png.Text {
+		"Title"       = png.Text{
+			keyword_localized = "タイトル",
+			language = "ja",
+			text ="PngSuite",
+		},
+		"Software"    = png.Text{
+			keyword_localized = "ソフトウェア",
+			language = "ja",
+			text = "\"pnmtopng\"を使用してNeXTstation色上に作成されます。",
+		},
+		"Description" = png.Text{
+			keyword_localized = "概要",
+			language = "ja",
+			text = "PNG形式の様々な色の種類をテストするために作成されたイメージのセットのコンパイル。含まれているのは透明度のフォーマットで、アルファチャネルを持つ、白黒、カラー、パレットです。すべてのビット深度が存在している仕様に従ったことができました。",
+		},
+	},
+}
+
+@test
+png_test :: proc(t: ^testing.T) {
+
+	total_tests    := 0
+	total_expected := 235
+
+	PNG_Suites := [][]PNG_Test{
+		Basic_PNG_Tests,
+		Interlaced_PNG_Tests,
+		Odd_Sized_PNG_Tests,
+		PNG_bKGD_Tests,
+		PNG_tRNS_Tests,
+		PNG_Filter_Tests,
+		PNG_Varied_IDAT_Tests,
+		PNG_ZLIB_Levels_Tests,
+		PNG_sPAL_Tests,
+		PNG_Ancillary_Tests,
+		Corrupt_PNG_Tests,
+
+		No_Postprocesing_Tests,
+
+	}
+
+	for suite in PNG_Suites {
+		total_tests += run_png_suite(t, suite)
+	}
+
+	error  := fmt.tprintf("Expected %v PNG tests, %v ran.", total_expected, total_tests)
+	expect(t, total_tests == total_expected, error)
+}
+
+run_png_suite :: proc(t: ^testing.T, suite: []PNG_Test) -> (subtotal: int) {
+
+	context = runtime.default_context()
+
+	for file in suite {
+		test_file := fmt.tprintf("%v/%v.png", TEST_SUITE_PATH, file.file)
+
+		img: ^png.Image
+		err: png.Error
+
+		count := 0
+		for test in file.tests {
+			count        += 1
+			subtotal     += 1
+			passed       := false
+
+			track: mem.Tracking_Allocator
+			mem.tracking_allocator_init(&track, context.allocator)
+			context.allocator = mem.tracking_allocator(&track)
+
+			img, err = png.load(test_file, test.options)
+
+			error  := fmt.tprintf("%v failed with %v.", test_file, err)
+
+			passed = (test.expected_error == nil && err == nil) || (test.expected_error == err)
+
+			expect(t, passed, error)
+
+			if err == nil { // No point in running the other tests if it didn't load.
+				pixels := bytes.buffer_to_bytes(&img.pixels)
+
+				// This struct compare fails at -opt:2 if PNG_Dims is not #packed.
+
+				dims   := PNG_Dims{img.width, img.height, img.channels, img.depth}
+				error  = fmt.tprintf("%v has %v, expected: %v.", file.file, dims, test.dims)
+
+				dims_pass := test.dims == dims
+
+				expect(t, dims_pass, error)
+
+				passed &= dims_pass
+
+				hash   := hash.crc32(pixels)
+				error  = fmt.tprintf("%v test %v hash is %08x, expected %08x.", file.file, count, hash, test.hash)
+				expect(t, test.hash == hash, error)
+
+				passed &= test.hash == hash
+				if .return_metadata in test.options {
+					v: ^png.Info
+
+					if img.metadata_ptr != nil && img.metadata_type == png.Info {
+						v = (^png.Info)(img.metadata_ptr)
+						for c in v.chunks {
+							#partial switch(c.header.type) {
+							case .gAMA:
+								switch(file.file) {
+								case "pp0n2c16", "pp0n6a08":
+									gamma := png.gamma(c)
+									expected_gamma := f32(1.0)
+									error  = fmt.tprintf("%v test %v gAMA is %v, expected %v.", file.file, count, gamma, expected_gamma)
+									expect(t, gamma == expected_gamma, error)
+								}
+							case .PLTE:
+								switch(file.file) {
+								case "pp0n2c16", "pp0n6a08":
+									plte, plte_ok := png.plte(c)
+
+									expected_plte_len := u16(216)
+									error  = fmt.tprintf("%v test %v PLTE length is %v, expected %v.", file.file, count, plte.used, expected_plte_len)
+									expect(t, expected_plte_len == plte.used && plte_ok, error)
+								}
+							case .sPLT:
+								switch(file.file) {
+								case "ps1n0g08", "ps1n2c16", "ps2n0g08", "ps2n2c16":
+									splt, splt_ok := png.splt(c)
+
+									expected_splt_len  := u16(216)
+									error  = fmt.tprintf("%v test %v sPLT length is %v, expected %v.", file.file, count, splt.used, expected_splt_len)
+									expect(t, expected_splt_len == splt.used && splt_ok, error)
+
+									expected_splt_name := "six-cube"
+									error  = fmt.tprintf("%v test %v sPLT name is %v, expected %v.", file.file, count, splt.name, expected_splt_name)
+									expect(t, expected_splt_name == splt.name && splt_ok, error)
+
+									png.splt_destroy(splt)
+								}
+							case .cHRM:
+								switch(file.file) {
+								case "ccwn2c08", "ccwn3p08":
+									chrm, chrm_ok := png.chrm(c)
+									expected_chrm := png.cHRM{
+										w = png.CIE_1931{x = 0.3127, y = 0.3290},
+										r = png.CIE_1931{x = 0.6400, y = 0.3300},
+										g = png.CIE_1931{x = 0.3000, y = 0.6000},
+										b = png.CIE_1931{x = 0.1500, y = 0.0600},
+									}
+									error  = fmt.tprintf("%v test %v cHRM is %v, expected %v.", file.file, count, chrm, expected_chrm)
+									expect(t, expected_chrm == chrm && chrm_ok, error)
+								}
+							case .pHYs:
+								phys     := png.phys(c)
+								phys_err := "%v test %v cHRM is %v, expected %v."
+								switch (file.file) {
+								case "cdfn2c08":
+									expected_phys := png.pHYs{ppu_x =    1, ppu_y =    4, unit = .Unknown}
+									error  = fmt.tprintf(phys_err, file.file, count, phys, expected_phys)
+									expect(t, expected_phys == phys, error)
+								case "cdhn2c08":
+									expected_phys := png.pHYs{ppu_x =    4, ppu_y =    1, unit = .Unknown}
+									error  = fmt.tprintf(phys_err, file.file, count, phys, expected_phys)
+									expect(t, expected_phys == phys, error)
+								case "cdsn2c08":
+									expected_phys := png.pHYs{ppu_x =    1, ppu_y =    1, unit = .Unknown}
+									error  = fmt.tprintf(phys_err, file.file, count, phys, expected_phys)
+									expect(t, expected_phys == phys, error)
+								case "cdun2c08":
+									expected_phys := png.pHYs{ppu_x = 1000, ppu_y = 1000, unit = .Meter}
+									error  = fmt.tprintf(phys_err, file.file, count, phys, expected_phys)
+									expect(t, expected_phys == phys, error)
+								}
+							case .hIST:
+								hist, hist_ok := png.hist(c)
+								hist_err := "%v test %v hIST has %v entries, expected %v."
+								switch (file.file) {
+								case "ch1n3p04":
+									error  = fmt.tprintf(hist_err, file.file, count, hist.used, 15)
+									expect(t, hist.used == 15 && hist_ok, error)
+								case "ch2n3p08":
+									error  = fmt.tprintf(hist_err, file.file, count, hist.used, 256)
+									expect(t, hist.used == 256 && hist_ok, error)
+								}
+							case .tIME:
+								png_time := png.time(c)
+								time_err := "%v test %v tIME was %v, expected %v."
+								expected_time: png.tIME
+
+								core_time, core_time_ok := png.core_time(c)
+								time_core_err := "%v test %v tIME->core:time is %v, expected %v."
+								expected_core: time.Time
+
+								switch(file.file) {
+								case "cm0n0g04": // modification time, 01-jan-2000 12:34:56
+									expected_time = png.tIME{year = 2000, month =  1, day =  1, hour = 12, minute = 34, second = 56}
+									expected_core = time.Time{_nsec = 946730096000000000}
+								case "cm7n0g04": // modification time, 01-jan-1970 00:00:00
+									expected_time = png.tIME{year = 1970, month =  1, day =  1, hour =  0, minute =  0, second =  0}
+									expected_core = time.Time{_nsec =                  0}
+								case "cm9n0g04": // modification time, 31-dec-1999 23:59:59
+									expected_time = png.tIME{year = 1999, month = 12, day = 31, hour = 23, minute = 59, second = 59}
+									expected_core = time.Time{_nsec = 946684799000000000}
+
+								}
+								error  = fmt.tprintf(time_err, file.file, count, png_time, expected_time)
+								expect(t, png_time == expected_time, error)
+
+								error  = fmt.tprintf(time_core_err, file.file, count, core_time, expected_core)
+								expect(t, core_time == expected_core && core_time_ok, error)
+							case .sBIT:
+								sbit, sbit_ok  := png.sbit(c)
+								sbit_err       := "%v test %v sBIT was %v, expected %v."
+								expected_sbit: [4]u8
+
+								switch (file.file) {
+								case "cs3n2c16": // color, 13 significant bits
+									expected_sbit = [4]u8{13, 13, 13,  0}
+								case "cs3n3p08": // paletted, 3 significant bits
+									expected_sbit = [4]u8{ 3,  3,  3,  0}
+								case "cs5n2c08": // color, 5 significant bits
+									expected_sbit = [4]u8{ 5,  5,  5,  0}
+								case "cs5n3p08": // paletted, 5 significant bits
+									expected_sbit = [4]u8{ 5,  5,  5,  0}
+								case "cs8n2c08": // color, 8 significant bits (reference)
+									expected_sbit = [4]u8{ 8,  8,  8,  0}
+								case "cs8n3p08": // paletted, 8 significant bits (reference)
+									expected_sbit = [4]u8{ 8,  8,  8,  0}
+								case "cdfn2c08", "cdhn2c08", "cdsn2c08", "cdun2c08", "ch1n3p04", "basn3p04":
+									expected_sbit = [4]u8{ 4,  4,  4,  0}
+								}
+								error  = fmt.tprintf(sbit_err, file.file, count, sbit, expected_sbit)
+								expect(t, sbit == expected_sbit && sbit_ok, error)
+							case .tEXt, .zTXt:
+								text, text_ok := png.text(c)
+								defer png.text_destroy(text)
+
+								switch(file.file) {
+								case "ct1n0g04": // with textual data
+									fallthrough
+								case "ctzn0g04": // with compressed textual data
+									if file.file in Expected_Text {
+										if text.keyword in Expected_Text[file.file] {
+											test_text := Expected_Text[file.file][text.keyword].text
+											error  = fmt.tprintf("%v test %v text keyword {{%v}}:'%v', expected '%v'.", file.file, count, text.keyword, text.text, test_text)
+											expect(t, text.text == test_text && text_ok, error)
+										}
+									}
+								}
+							case .iTXt:
+								text, text_ok := png.text(c)
+								defer png.text_destroy(text)
+
+								switch(file.file) {
+								case "cten0g04": // international UTF-8, english
+									if file.file in Expected_Text {
+										if text.keyword in Expected_Text[file.file] {
+											test := Expected_Text[file.file][text.keyword]
+											error  = fmt.tprintf("%v test %v text keyword {{%v}}:'%v', expected '%v'.", file.file, count, text.keyword, text, test)
+											expect(t, text.language == test.language && text_ok, error)
+											expect(t, text.keyword_localized == test.keyword_localized && text_ok, error)
+										}
+									}
+								case "ctfn0g04": // international UTF-8, finnish
+									if file.file in Expected_Text {
+										if text.keyword in Expected_Text[file.file] {
+											test := Expected_Text[file.file][text.keyword]
+											error  = fmt.tprintf("%v test %v text keyword {{%v}}:'%v', expected '%v'.", file.file, count, text.keyword, text, test)
+											expect(t, text.text == test.text && text_ok, error)
+											expect(t, text.language == test.language && text_ok, error)
+											expect(t, text.keyword_localized == test.keyword_localized && text_ok, error)
+										}
+									}
+								case "ctgn0g04": // international UTF-8, greek
+									if file.file in Expected_Text {
+										if text.keyword in Expected_Text[file.file] {
+											test := Expected_Text[file.file][text.keyword]
+											error  = fmt.tprintf("%v test %v text keyword {{%v}}:'%v', expected '%v'.", file.file, count, text.keyword, text, test)
+											expect(t, text.text == test.text && text_ok, error)
+											expect(t, text.language == test.language && text_ok, error)
+											expect(t, text.keyword_localized == test.keyword_localized && text_ok, error)
+										}
+									}
+								case "cthn0g04": // international UTF-8, hindi
+									if file.file in Expected_Text {
+										if text.keyword in Expected_Text[file.file] {
+											test := Expected_Text[file.file][text.keyword]
+											error  = fmt.tprintf("%v test %v text keyword {{%v}}:'%v', expected '%v'.", file.file, count, text.keyword, text, test)
+											expect(t, text.text == test.text && text_ok, error)
+											expect(t, text.language == test.language && text_ok, error)
+											expect(t, text.keyword_localized == test.keyword_localized && text_ok, error)
+										}
+									}
+								case "ctjn0g04": // international UTF-8, japanese
+									if file.file in Expected_Text {
+										if text.keyword in Expected_Text[file.file] {
+											test := Expected_Text[file.file][text.keyword]
+											error  = fmt.tprintf("%v test %v text keyword {{%v}}:'%v', expected '%v'.", file.file, count, text.keyword, text, test)
+											expect(t, text.text == test.text && text_ok, error)
+											expect(t, text.language == test.language && text_ok, error)
+											expect(t, text.keyword_localized == test.keyword_localized && text_ok, error)
+										}
+									}
+								}
+							case .eXIf:
+								if file.file == "exif2c08" { // chunk with jpeg exif data
+									exif, exif_ok := png.exif(c)
+									error      = fmt.tprintf("%v test %v eXIf byte order '%v', expected 'big_endian'.", file.file, count, exif.byte_order)
+									error_len := fmt.tprintf("%v test %v eXIf data length '%v', expected '%v'.", file.file, len(exif.data), 978)
+									expect(t, exif.byte_order == .big_endian && exif_ok, error)
+									expect(t, len(exif.data)  == 978         && exif_ok, error_len)
+								}
+							}
+						}
+					}
+				}
+			}
+
+			if WRITE_PPM_ON_FAIL && !passed && err == nil { // It loaded but had an error in its compares.
+				testing.logf(t, "Test failed, writing ppm/%v-%v.ppm to help debug.\n", file.file, count)
+				output := fmt.tprintf("ppm/%v-%v.ppm", file.file, count)
+				write_image_as_ppm(output, img)
+			}
+
+			png.destroy(img)
+
+			for _, v in track.allocation_map {
+				error = fmt.tprintf("%v test %v leaked %v bytes @ loc %v.", file.file, count, v.size, v.location)
+				expect(t, false, error)
+			}
+		}
+	}
+
+	return
+}
+
+// Crappy PPM writer used during testing. Don't use in production.
+write_image_as_ppm :: proc(filename: string, image: ^image.Image) -> (success: bool) {
+
+	_bg :: proc(x, y: int, high := true) -> (res: [3]u16) {
+		if high {
+			l := u16(30 * 256 + 30)
+
+			if (x & 4 == 0) ~ (y & 4 == 0) {
+				res = [3]u16{l, l, l}
+			} else {
+				res = [3]u16{l >> 1, l >> 1, l >> 1}
+			}
+		} else {
+			if (x & 4 == 0) ~ (y & 4 == 0) {
+				res = [3]u16{30, 30, 30}
+			} else {
+				res = [3]u16{15, 15, 15}
+			}
+		}
+		return
+	}
+
+	using image
+	using os
+
+	flags: int = O_WRONLY|O_CREATE|O_TRUNC
+
+	img := image
+
+	// PBM 16-bit images are big endian
+	when ODIN_ENDIAN == "little" {
+		if img.depth == 16 {
+			// The pixel components are in Big Endian. Let's byteswap back.
+			input  := mem.slice_data_cast([]u16,   img.pixels.buf[:])
+			output := mem.slice_data_cast([]u16be, img.pixels.buf[:])
+			#no_bounds_check for v, i in input {
+				output[i] = u16be(v)
+			}
+		}
+	}
+
+	pix := bytes.buffer_to_bytes(&img.pixels)
+
+	if len(pix) == 0 || len(pix) < image.width * image.height * int(image.channels) {
+		return false
+	}
+
+	mode: int = 0
+	when ODIN_OS == "linux" || ODIN_OS == "darwin" {
+		// NOTE(justasd): 644 (owner read, write; group read; others read)
+		mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH
+	}
+
+	fd, err := open(filename, flags, mode)
+	if err != 0 {
+		return false
+	}
+	defer close(fd)
+
+	write_string(fd,
+		fmt.tprintf("P6\n%v %v\n%v\n", width, height, (1 << uint(depth) -1)),
+	)
+
+	if channels == 3 {
+		// We don't handle transparency here...
+		write_ptr(fd, raw_data(pix), len(pix))
+	} else {
+		bpp := depth == 16 ? 2 : 1
+		bytes_needed := width * height * 3 * bpp
+
+		op := bytes.Buffer{}
+		bytes.buffer_init_allocator(&op, bytes_needed, bytes_needed)
+		defer bytes.buffer_destroy(&op)
+
+		if channels == 1 {
+			if depth == 16 {
+				assert(len(pix) == width * height * 2)
+				p16 := mem.slice_data_cast([]u16, pix)
+				o16 := mem.slice_data_cast([]u16, op.buf[:])
+				#no_bounds_check for len(p16) != 0 {
+					r := u16(p16[0])
+					o16[0] = r
+					o16[1] = r
+					o16[2] = r
+					p16 = p16[1:]
+					o16 = o16[3:]
+				}
+			} else {
+				o := 0
+				for i := 0; i < len(pix); i += 1 {
+					r := pix[i]
+					op.buf[o  ] = r
+					op.buf[o+1] = r
+					op.buf[o+2] = r
+					o += 3
+				}
+			}
+			write_ptr(fd, raw_data(op.buf), len(op.buf))
+		} else if channels == 2 {
+			if depth == 16 {
+				p16 := mem.slice_data_cast([]u16, pix)
+				o16 := mem.slice_data_cast([]u16, op.buf[:])
+
+				bgcol := img.background
+
+				#no_bounds_check for len(p16) != 0 {
+					r  := f64(u16(p16[0]))
+					bg:   f64
+					if bgcol != nil {
+						v := bgcol.([3]u16)[0]
+						bg = f64(v)
+					}
+					a  := f64(u16(p16[1])) / 65535.0
+					l  := (a * r) + (1 / a) * bg
+
+					o16[0] = u16(l)
+					o16[1] = u16(l)
+					o16[2] = u16(l)
+
+					p16 = p16[2:]
+					o16 = o16[3:]
+				}
+			} else {
+				o := 0
+				for i := 0; i < len(pix); i += 2 {
+					r := pix[i]; a := pix[i+1]; a1 := f32(a) / 255.0
+					c := u8(f32(r) * a1)
+					op.buf[o  ] = c
+					op.buf[o+1] = c
+					op.buf[o+2] = c
+					o += 3
+				}
+			}
+			write_ptr(fd, raw_data(op.buf), len(op.buf))
+		} else if channels == 4 {
+			if depth == 16 {
+				p16 := mem.slice_data_cast([]u16be, pix)
+				o16 := mem.slice_data_cast([]u16be, op.buf[:])
+
+				i := 0
+				for len(p16) > 0 {
+					i += 1
+					x  := i  % width
+					y  := i / width
+					bg := _bg(x, y, true)
+
+					r     := f32(p16[0])
+					g     := f32(p16[1])
+					b     := f32(p16[2])
+					a     := f32(p16[3]) / 65535.0
+
+					lr  := (a * r) + (1 / a) * f32(bg[0])
+					lg  := (a * g) + (1 / a) * f32(bg[1])
+					lb  := (a * b) + (1 / a) * f32(bg[2])
+
+					o16[0] = u16be(lr)
+					o16[1] = u16be(lg)
+					o16[2] = u16be(lb)
+
+					p16 = p16[4:]
+					o16 = o16[3:]
+				}
+			} else {
+				o := 0
+
+				for i := 0; i < len(pix); i += 4 {
+
+					x := (i / 4)  % width
+					y := i / width / 4
+					_b := _bg(x, y, false)
+					bgcol := [3]u8{u8(_b[0]), u8(_b[1]), u8(_b[2])}
+
+					r := f32(pix[i])
+					g := f32(pix[i+1])
+					b := f32(pix[i+2])
+					a := f32(pix[i+3]) / 255.0
+
+					lr := u8(f32(r) * a + (1 / a) * f32(bgcol[0]))
+					lg := u8(f32(g) * a + (1 / a) * f32(bgcol[1]))
+					lb := u8(f32(b) * a + (1 / a) * f32(bgcol[2]))
+					op.buf[o  ] = lr
+					op.buf[o+1] = lg
+					op.buf[o+2] = lb
+					o += 3
+				}
+			}
+			write_ptr(fd, raw_data(op.buf), len(op.buf))
+		} else {
+			return false
+		}
+	}
+	return true
+}