AtomicGameEngine/Source/ThirdParty/JO/jo_jpeg.cpp

/* public domain Simple, Minimalistic JPEG writer - http://jonolick.com
 *
 * Quick Notes:
 * 	Based on a javascript jpeg writer
 * 	JPEG baseline (no JPEG progressive)
 * 	Supports 1, 3 or 4 component input. (luminance, RGB or RGBX)
 *
 * Latest revisions:
 *	1.52 (2012-22-11) Added support for specifying Luminance, RGB, or RGBA via comp(onents) argument (1, 3 and 4 respectively). 
 *	1.51 (2012-19-11) Fixed some warnings
 *	1.50 (2012-18-11) MT safe. Simplified. Optimized. Reduced memory requirements. Zero allocations. No namespace polution. Approx 340 lines code.
 *	1.10 (2012-16-11) compile fixes, added docs,
 *		changed from .h to .cpp (simpler to bootstrap), etc
 * 	1.00 (2012-02-02) initial release
 *
 * Basic usage:
 *	char *foo = new char[128*128*4]; // 4 component. RGBX format, where X is unused 
 *	jo_write_jpg("foo.jpg", foo, 128, 128, 4, 90); // comp can be 1, 3, or 4. Lum, RGB, or RGBX respectively.
 * 	
 * */

// Modified by Lasse Oorni for Urho3D

#ifndef JO_JPEG_HEADER_FILE_ONLY

#if defined(_MSC_VER) && _MSC_VER >= 0x1400
#define _CRT_SECURE_NO_WARNINGS // suppress warnings about fopen()
#endif

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

// Urho3D: for MultiByteToWideChar
#ifdef _WIN32
#include <windows.h>
#endif

static const unsigned char s_jo_ZigZag[] = { 0,1,5,6,14,15,27,28,2,4,7,13,16,26,29,42,3,8,12,17,25,30,41,43,9,11,18,24,31,40,44,53,10,19,23,32,39,45,52,54,20,22,33,38,46,51,55,60,21,34,37,47,50,56,59,61,35,36,48,49,57,58,62,63 };

static void jo_writeBits(FILE *fp, int &bitBuf, int &bitCnt, const unsigned short *bs) {
	bitCnt += bs[1];
	bitBuf |= bs[0] << (24 - bitCnt);
	while(bitCnt >= 8) {
		unsigned char c = (bitBuf >> 16) & 255;
		putc(c, fp);
		if(c == 255) {
			putc(0, fp);
		}
		bitBuf <<= 8;
		bitCnt -= 8;
	}
}

static void jo_DCT(float &d0, float &d1, float &d2, float &d3, float &d4, float &d5, float &d6, float &d7) {
	float tmp0 = d0 + d7;
	float tmp7 = d0 - d7;
	float tmp1 = d1 + d6;
	float tmp6 = d1 - d6;
	float tmp2 = d2 + d5;
	float tmp5 = d2 - d5;
	float tmp3 = d3 + d4;
	float tmp4 = d3 - d4;

	// Even part
	float tmp10 = tmp0 + tmp3;	// phase 2
	float tmp13 = tmp0 - tmp3;
	float tmp11 = tmp1 + tmp2;
	float tmp12 = tmp1 - tmp2;

	d0 = tmp10 + tmp11; 		// phase 3
	d4 = tmp10 - tmp11;

	float z1 = (tmp12 + tmp13) * 0.707106781f; // c4
	d2 = tmp13 + z1; 		// phase 5
	d6 = tmp13 - z1;

	// Odd part
	tmp10 = tmp4 + tmp5; 		// phase 2
	tmp11 = tmp5 + tmp6;
	tmp12 = tmp6 + tmp7;

	// The rotator is modified from fig 4-8 to avoid extra negations.
	float z5 = (tmp10 - tmp12) * 0.382683433f; // c6
	float z2 = tmp10 * 0.541196100f + z5; // c2-c6
	float z4 = tmp12 * 1.306562965f + z5; // c2+c6
	float z3 = tmp11 * 0.707106781f; // c4

	float z11 = tmp7 + z3;		// phase 5
	float z13 = tmp7 - z3;

	d5 = z13 + z2;			// phase 6
	d3 = z13 - z2;
	d1 = z11 + z4;
	d7 = z11 - z4;
} 

static void jo_calcBits(int val, unsigned short bits[2]) {
	int tmp1 = val < 0 ? -val : val;
	val = val < 0 ? val-1 : val;
	bits[1] = 1;
	while(tmp1 >>= 1) {
		++bits[1];
	}
	bits[0] = val & ((1<<bits[1])-1);
}

static int jo_processDU(FILE *fp, int &bitBuf, int &bitCnt, float *CDU, float *fdtbl, int DC, const unsigned short HTDC[256][2], const unsigned short HTAC[256][2]) {
	const unsigned short EOB[2] = { HTAC[0x00][0], HTAC[0x00][1] };
	const unsigned short M16zeroes[2] = { HTAC[0xF0][0], HTAC[0xF0][1] };

	// DCT rows
	for(int dataOff=0; dataOff<64; dataOff+=8) {
		jo_DCT(CDU[dataOff], CDU[dataOff+1], CDU[dataOff+2], CDU[dataOff+3], CDU[dataOff+4], CDU[dataOff+5], CDU[dataOff+6], CDU[dataOff+7]);
	}
	// DCT columns
	for(int dataOff=0; dataOff<8; ++dataOff) {
		jo_DCT(CDU[dataOff], CDU[dataOff+8], CDU[dataOff+16], CDU[dataOff+24], CDU[dataOff+32], CDU[dataOff+40], CDU[dataOff+48], CDU[dataOff+56]);
	}
	// Quantize/descale/zigzag the coefficients
	int DU[64];
	for(int i=0; i<64; ++i) {
		float v = CDU[i]*fdtbl[i];
		DU[s_jo_ZigZag[i]] = (int)(v < 0 ? ceilf(v - 0.5f) : floorf(v + 0.5f));
	}

	// Encode DC
	int diff = DU[0] - DC; 
	if (diff == 0) {
		jo_writeBits(fp, bitBuf, bitCnt, HTDC[0]);
	} else {
		unsigned short bits[2];
		jo_calcBits(diff, bits);
		jo_writeBits(fp, bitBuf, bitCnt, HTDC[bits[1]]);
		jo_writeBits(fp, bitBuf, bitCnt, bits);
	}
	// Encode ACs
	int end0pos = 63;
	for(; (end0pos>0)&&(DU[end0pos]==0); --end0pos) {
	}
	// end0pos = first element in reverse order !=0
	if(end0pos == 0) {
		jo_writeBits(fp, bitBuf, bitCnt, EOB);
		return DU[0];
	}
	for(int i = 1; i <= end0pos; ++i) {
		int startpos = i;
		for (; DU[i]==0 && i<=end0pos; ++i) {
		}
		int nrzeroes = i-startpos;
		if ( nrzeroes >= 16 ) {
			int lng = nrzeroes>>4;
			for (int nrmarker=1; nrmarker <= lng; ++nrmarker)
				jo_writeBits(fp, bitBuf, bitCnt, M16zeroes);
			nrzeroes &= 15;
		}
		unsigned short bits[2];
		jo_calcBits(DU[i], bits);
		jo_writeBits(fp, bitBuf, bitCnt, HTAC[(nrzeroes<<4)+bits[1]]);
		jo_writeBits(fp, bitBuf, bitCnt, bits);
	}
	if(end0pos != 63) {
		jo_writeBits(fp, bitBuf, bitCnt, EOB);
	}
	return DU[0];
}

bool jo_write_jpg(const char *filename, const void *data, int width, int height, int comp, int quality) {
	// Constants that don't pollute global namespace
	static const unsigned char std_dc_luminance_nrcodes[] = {0,0,1,5,1,1,1,1,1,1,0,0,0,0,0,0,0};
	static const unsigned char std_dc_luminance_values[] = {0,1,2,3,4,5,6,7,8,9,10,11};
	static const unsigned char std_ac_luminance_nrcodes[] = {0,0,2,1,3,3,2,4,3,5,5,4,4,0,0,1,0x7d};
	static const unsigned char std_ac_luminance_values[] = {
		0x01,0x02,0x03,0x00,0x04,0x11,0x05,0x12,0x21,0x31,0x41,0x06,0x13,0x51,0x61,0x07,0x22,0x71,0x14,0x32,0x81,0x91,0xa1,0x08,
		0x23,0x42,0xb1,0xc1,0x15,0x52,0xd1,0xf0,0x24,0x33,0x62,0x72,0x82,0x09,0x0a,0x16,0x17,0x18,0x19,0x1a,0x25,0x26,0x27,0x28,
		0x29,0x2a,0x34,0x35,0x36,0x37,0x38,0x39,0x3a,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0x4a,0x53,0x54,0x55,0x56,0x57,0x58,0x59,
		0x5a,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0x6a,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7a,0x83,0x84,0x85,0x86,0x87,0x88,0x89,
		0x8a,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9a,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,0xa8,0xa9,0xaa,0xb2,0xb3,0xb4,0xb5,0xb6,
		0xb7,0xb8,0xb9,0xba,0xc2,0xc3,0xc4,0xc5,0xc6,0xc7,0xc8,0xc9,0xca,0xd2,0xd3,0xd4,0xd5,0xd6,0xd7,0xd8,0xd9,0xda,0xe1,0xe2,
		0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,0xea,0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,0xf9,0xfa
	};
	static const unsigned char std_dc_chrominance_nrcodes[] = {0,0,3,1,1,1,1,1,1,1,1,1,0,0,0,0,0};
	static const unsigned char std_dc_chrominance_values[] = {0,1,2,3,4,5,6,7,8,9,10,11};
	static const unsigned char std_ac_chrominance_nrcodes[] = {0,0,2,1,2,4,4,3,4,7,5,4,4,0,1,2,0x77};
	static const unsigned char std_ac_chrominance_values[] = {
		0x00,0x01,0x02,0x03,0x11,0x04,0x05,0x21,0x31,0x06,0x12,0x41,0x51,0x07,0x61,0x71,0x13,0x22,0x32,0x81,0x08,0x14,0x42,0x91,
		0xa1,0xb1,0xc1,0x09,0x23,0x33,0x52,0xf0,0x15,0x62,0x72,0xd1,0x0a,0x16,0x24,0x34,0xe1,0x25,0xf1,0x17,0x18,0x19,0x1a,0x26,
		0x27,0x28,0x29,0x2a,0x35,0x36,0x37,0x38,0x39,0x3a,0x43,0x44,0x45,0x46,0x47,0x48,0x49,0x4a,0x53,0x54,0x55,0x56,0x57,0x58,
		0x59,0x5a,0x63,0x64,0x65,0x66,0x67,0x68,0x69,0x6a,0x73,0x74,0x75,0x76,0x77,0x78,0x79,0x7a,0x82,0x83,0x84,0x85,0x86,0x87,
		0x88,0x89,0x8a,0x92,0x93,0x94,0x95,0x96,0x97,0x98,0x99,0x9a,0xa2,0xa3,0xa4,0xa5,0xa6,0xa7,0xa8,0xa9,0xaa,0xb2,0xb3,0xb4,
		0xb5,0xb6,0xb7,0xb8,0xb9,0xba,0xc2,0xc3,0xc4,0xc5,0xc6,0xc7,0xc8,0xc9,0xca,0xd2,0xd3,0xd4,0xd5,0xd6,0xd7,0xd8,0xd9,0xda,
		0xe2,0xe3,0xe4,0xe5,0xe6,0xe7,0xe8,0xe9,0xea,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,0xf8,0xf9,0xfa
	};
	// Huffman tables
	static const unsigned short YDC_HT[256][2] = { {0,2},{2,3},{3,3},{4,3},{5,3},{6,3},{14,4},{30,5},{62,6},{126,7},{254,8},{510,9}};
	static const unsigned short UVDC_HT[256][2] = { {0,2},{1,2},{2,2},{6,3},{14,4},{30,5},{62,6},{126,7},{254,8},{510,9},{1022,10},{2046,11}};
	static const unsigned short YAC_HT[256][2] = { 
		{10,4},{0,2},{1,2},{4,3},{11,4},{26,5},{120,7},{248,8},{1014,10},{65410,16},{65411,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{12,4},{27,5},{121,7},{502,9},{2038,11},{65412,16},{65413,16},{65414,16},{65415,16},{65416,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{28,5},{249,8},{1015,10},{4084,12},{65417,16},{65418,16},{65419,16},{65420,16},{65421,16},{65422,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{58,6},{503,9},{4085,12},{65423,16},{65424,16},{65425,16},{65426,16},{65427,16},{65428,16},{65429,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{59,6},{1016,10},{65430,16},{65431,16},{65432,16},{65433,16},{65434,16},{65435,16},{65436,16},{65437,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{122,7},{2039,11},{65438,16},{65439,16},{65440,16},{65441,16},{65442,16},{65443,16},{65444,16},{65445,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{123,7},{4086,12},{65446,16},{65447,16},{65448,16},{65449,16},{65450,16},{65451,16},{65452,16},{65453,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{250,8},{4087,12},{65454,16},{65455,16},{65456,16},{65457,16},{65458,16},{65459,16},{65460,16},{65461,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{504,9},{32704,15},{65462,16},{65463,16},{65464,16},{65465,16},{65466,16},{65467,16},{65468,16},{65469,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{505,9},{65470,16},{65471,16},{65472,16},{65473,16},{65474,16},{65475,16},{65476,16},{65477,16},{65478,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{506,9},{65479,16},{65480,16},{65481,16},{65482,16},{65483,16},{65484,16},{65485,16},{65486,16},{65487,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{1017,10},{65488,16},{65489,16},{65490,16},{65491,16},{65492,16},{65493,16},{65494,16},{65495,16},{65496,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{1018,10},{65497,16},{65498,16},{65499,16},{65500,16},{65501,16},{65502,16},{65503,16},{65504,16},{65505,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{2040,11},{65506,16},{65507,16},{65508,16},{65509,16},{65510,16},{65511,16},{65512,16},{65513,16},{65514,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{65515,16},{65516,16},{65517,16},{65518,16},{65519,16},{65520,16},{65521,16},{65522,16},{65523,16},{65524,16},{0,0},{0,0},{0,0},{0,0},{0,0},
		{2041,11},{65525,16},{65526,16},{65527,16},{65528,16},{65529,16},{65530,16},{65531,16},{65532,16},{65533,16},{65534,16},{0,0},{0,0},{0,0},{0,0},{0,0}
	};
	static const unsigned short UVAC_HT[256][2] = { 
		{0,2},{1,2},{4,3},{10,4},{24,5},{25,5},{56,6},{120,7},{500,9},{1014,10},{4084,12},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{11,4},{57,6},{246,8},{501,9},{2038,11},{4085,12},{65416,16},{65417,16},{65418,16},{65419,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{26,5},{247,8},{1015,10},{4086,12},{32706,15},{65420,16},{65421,16},{65422,16},{65423,16},{65424,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{27,5},{248,8},{1016,10},{4087,12},{65425,16},{65426,16},{65427,16},{65428,16},{65429,16},{65430,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{58,6},{502,9},{65431,16},{65432,16},{65433,16},{65434,16},{65435,16},{65436,16},{65437,16},{65438,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{59,6},{1017,10},{65439,16},{65440,16},{65441,16},{65442,16},{65443,16},{65444,16},{65445,16},{65446,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{121,7},{2039,11},{65447,16},{65448,16},{65449,16},{65450,16},{65451,16},{65452,16},{65453,16},{65454,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{122,7},{2040,11},{65455,16},{65456,16},{65457,16},{65458,16},{65459,16},{65460,16},{65461,16},{65462,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{249,8},{65463,16},{65464,16},{65465,16},{65466,16},{65467,16},{65468,16},{65469,16},{65470,16},{65471,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{503,9},{65472,16},{65473,16},{65474,16},{65475,16},{65476,16},{65477,16},{65478,16},{65479,16},{65480,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{504,9},{65481,16},{65482,16},{65483,16},{65484,16},{65485,16},{65486,16},{65487,16},{65488,16},{65489,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{505,9},{65490,16},{65491,16},{65492,16},{65493,16},{65494,16},{65495,16},{65496,16},{65497,16},{65498,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{506,9},{65499,16},{65500,16},{65501,16},{65502,16},{65503,16},{65504,16},{65505,16},{65506,16},{65507,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{2041,11},{65508,16},{65509,16},{65510,16},{65511,16},{65512,16},{65513,16},{65514,16},{65515,16},{65516,16},{0,0},{0,0},{0,0},{0,0},{0,0},{0,0},
		{16352,14},{65517,16},{65518,16},{65519,16},{65520,16},{65521,16},{65522,16},{65523,16},{65524,16},{65525,16},{0,0},{0,0},{0,0},{0,0},{0,0},
		{1018,10},{32707,15},{65526,16},{65527,16},{65528,16},{65529,16},{65530,16},{65531,16},{65532,16},{65533,16},{65534,16},{0,0},{0,0},{0,0},{0,0},{0,0}
	};
	static const int YQT[] = {16,11,10,16,24,40,51,61,12,12,14,19,26,58,60,55,14,13,16,24,40,57,69,56,14,17,22,29,51,87,80,62,18,22,37,56,68,109,103,77,24,35,55,64,81,104,113,92,49,64,78,87,103,121,120,101,72,92,95,98,112,100,103,99};
	static const int UVQT[] = {17,18,24,47,99,99,99,99,18,21,26,66,99,99,99,99,24,26,56,99,99,99,99,99,47,66,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99,99};
	static const float aasf[] = { 1.0f * 2.828427125f, 1.387039845f * 2.828427125f, 1.306562965f * 2.828427125f, 1.175875602f * 2.828427125f, 1.0f * 2.828427125f, 0.785694958f * 2.828427125f, 0.541196100f * 2.828427125f, 0.275899379f * 2.828427125f };

	if(!data || !filename || !width || !height || comp > 4 || comp < 1 || comp == 2) {
		return false;
	}

	// Urho3D: proper UTF8 handling for Windows
#ifndef _WIN32
	FILE *fp = fopen(filename, "wb");
#else
	int wcharsize = MultiByteToWideChar(CP_UTF8, 0, filename, -1, NULL, 0);
	wchar_t* wstr = new wchar_t[wcharsize];
	MultiByteToWideChar(CP_UTF8, 0, filename, -1, wstr, wcharsize);
	FILE *fp = _wfopen(wstr, L"wb");
	delete[] wstr;
#endif
	if(!fp) {
		return false;
	}

	quality = quality ? quality : 90;
	quality = quality < 1 ? 1 : quality > 100 ? 100 : quality;
	quality = quality < 50 ? 5000 / quality : 200 - quality * 2;

	unsigned char YTable[64], UVTable[64];
	for(int i = 0; i < 64; ++i) {
		int yti = (YQT[i]*quality+50)/100;
		YTable[s_jo_ZigZag[i]] = yti < 1 ? 1 : yti > 255 ? 255 : yti;
		int uvti  = (UVQT[i]*quality+50)/100;
		UVTable[s_jo_ZigZag[i]] = uvti < 1 ? 1 : uvti > 255 ? 255 : uvti;
	}

	float fdtbl_Y[64], fdtbl_UV[64];
	for(int row = 0, k = 0; row < 8; ++row) {
		for(int col = 0; col < 8; ++col, ++k) {
			fdtbl_Y[k]  = 1 / (YTable [s_jo_ZigZag[k]] * aasf[row] * aasf[col]);
			fdtbl_UV[k] = 1 / (UVTable[s_jo_ZigZag[k]] * aasf[row] * aasf[col]);
		}
	}

	// Write Headers
	static const unsigned char head0[] = { 0xFF,0xD8,0xFF,0xE0,0,0x10,'J','F','I','F',0,1,1,0,0,1,0,1,0,0,0xFF,0xDB,0,0x84,0 };
	fwrite(head0, sizeof(head0), 1, fp);
	fwrite(YTable, sizeof(YTable), 1, fp);
	putc(1, fp);
	fwrite(UVTable, sizeof(UVTable), 1, fp);
    // Urho3D: modified to avoid narrowing conversion
	const unsigned char head1[] = { 0xFF,0xC0,0,0x11,8,static_cast<unsigned char>(height>>8),static_cast<unsigned char>(height&0xFF),static_cast<unsigned char>(width>>8),static_cast<unsigned char>(width&0xFF),3,1,0x11,0,2,0x11,1,3,0x11,1,0xFF,0xC4,0x01,0xA2,0 };
	fwrite(head1, sizeof(head1), 1, fp);
	fwrite(std_dc_luminance_nrcodes+1, sizeof(std_dc_luminance_nrcodes)-1, 1, fp);
	fwrite(std_dc_luminance_values, sizeof(std_dc_luminance_values), 1, fp);
	putc(0x10, fp); // HTYACinfo
	fwrite(std_ac_luminance_nrcodes+1, sizeof(std_ac_luminance_nrcodes)-1, 1, fp);
	fwrite(std_ac_luminance_values, sizeof(std_ac_luminance_values), 1, fp);
	putc(1, fp); // HTUDCinfo
	fwrite(std_dc_chrominance_nrcodes+1, sizeof(std_dc_chrominance_nrcodes)-1, 1, fp);
	fwrite(std_dc_chrominance_values, sizeof(std_dc_chrominance_values), 1, fp);
	putc(0x11, fp); // HTUACinfo
	fwrite(std_ac_chrominance_nrcodes+1, sizeof(std_ac_chrominance_nrcodes)-1, 1, fp);
	fwrite(std_ac_chrominance_values, sizeof(std_ac_chrominance_values), 1, fp);
	static const unsigned char head2[] = { 0xFF,0xDA,0,0xC,3,1,0,2,0x11,3,0x11,0,0x3F,0 };
	fwrite(head2, sizeof(head2), 1, fp);

	// Encode 8x8 macroblocks
	const unsigned char *imageData = (const unsigned char *)data;
	int DCY=0, DCU=0, DCV=0;
	int bitBuf=0, bitCnt=0;
	int ofsG = comp > 1 ? 1 : 0, ofsB = comp > 1 ? 2 : 0;
	for(int y = 0; y < height; y += 8) {
		for(int x = 0; x < width; x += 8) {
			float YDU[64], UDU[64], VDU[64];
			for(int row = y, pos = 0; row < y+8; ++row) {
				for(int col = x; col < x+8; ++col, ++pos) {
					int p = row*width*comp + col*comp;
					if(row >= height) {
						p -= width*comp*(row+1 - height);
					}
					if(col >= width) {
						p -= comp*(col+1 - width);
					}

					float r = imageData[p+0], g = imageData[p+ofsG], b = imageData[p+ofsB];
					YDU[pos]=+0.29900f*r+0.58700f*g+0.11400f*b-128;
					UDU[pos]=-0.16874f*r-0.33126f*g+0.50000f*b;
					VDU[pos]=+0.50000f*r-0.41869f*g-0.08131f*b;
				}
			}

			DCY = jo_processDU(fp, bitBuf, bitCnt, YDU, fdtbl_Y, DCY, YDC_HT, YAC_HT);
			DCU = jo_processDU(fp, bitBuf, bitCnt, UDU, fdtbl_UV, DCU, UVDC_HT, UVAC_HT);
			DCV = jo_processDU(fp, bitBuf, bitCnt, VDU, fdtbl_UV, DCV, UVDC_HT, UVAC_HT);
		}
	}
	
	// Do the bit alignment of the EOI marker
	static const unsigned short fillBits[] = {0x7F, 7};
	jo_writeBits(fp, bitBuf, bitCnt, fillBits);

	// EOI
	putc(0xFF, fp);
	putc(0xD9, fp);

	fclose(fp);
	return true;
}

#endif