static void
cvtClump(unsigned char* op, uint32* raster, uint32 ch, uint32 cw, uint32 w)
{
float Y, Cb = 0, Cr = 0;
uint32 j, k;
/*
* Convert ch-by-cw block of RGB
* to YCbCr and sample accordingly.
*/
for (k = 0; k < ch; k++) {
for (j = 0; j < cw; j++) {
uint32 RGB = (raster - k*w)[j];
Y = lumaRed[TIFFGetR(RGB)] +
lumaGreen[TIFFGetG(RGB)] +
lumaBlue[TIFFGetB(RGB)];
/* accumulate chrominance */
Cb += (TIFFGetB(RGB) - Y) * D1;
Cr += (TIFFGetR(RGB) - Y) * D2;
/* emit luminence */
*op++ = V2Code(Y,
refBlackWhite[0], refBlackWhite[1], 255);
}
for (; j < horizSubSampling; j++)
*op++ = Yzero;
}
for (; k < vertSubSampling; k++) {
for (j = 0; j < horizSubSampling; j++)
*op++ = Yzero;
}
/* emit sampled chrominance values */
*op++ = V2Code(Cb / (ch*cw), refBlackWhite[2], refBlackWhite[3], 127);
*op++ = V2Code(Cr / (ch*cw), refBlackWhite[4], refBlackWhite[5], 127);
}
static
void
check(int R, int G, int B)
{
float Y, Cb, Cr;
int iY, iCb, iCr;
float rY, rCb, rCr;
float rR, rG, rB;
int eR, eG, eB;
Y = lumaRed[R] + lumaGreen[G] + lumaBlue[B];
Cb = (B - Y)*D2;
Cr = (R - Y)*D1;
iY = V2Code(Y, refBlackWhite[0], refBlackWhite[1], 255);
iCb = V2Code(Cb, refBlackWhite[2], refBlackWhite[3], 127);
iCr = V2Code(Cr, refBlackWhite[4], refBlackWhite[5], 127);
rCb = Code2V(iCb, refBlackWhite[2], refBlackWhite[3], 127);
rCr = Code2V(iCr, refBlackWhite[4], refBlackWhite[5], 127);
rY = Code2V(iY, refBlackWhite[0], refBlackWhite[1], 255);
rR = rY + rCr*D3;
rB = rY + rCb*D4;
rG = rY - rCb*D6 - rCr*D5;
eR = R - CLAMP(rR,0,255);
eG = G - CLAMP(rG,0,255);
eB = B - CLAMP(rB,0,255);
if (abs(eR) > 1 || abs(eG) > 1 || abs(eB) > 1) {
printf("R %u G %u B %u", R, G, B);
printf(" Y %g Cb %g Cr %g", Y, Cb, Cr);
printf(" iY %u iCb %u iCr %u", iY, iCb, iCr);
printf("\n -> Y %g Cb %g Cr %g", rY, rCb, rCr);
printf(" R %g (%u) G %g (%u) B %g (%u) E=[%d %d %d])\n"
, rR, CLAMP(rR,0,255)
, rG, CLAMP(rG,0,255)
, rB, CLAMP(rB,0,255)
, eR, eG, eB
);
}
eRtotal += eR;
eGtotal += eG;
eBtotal += eB;
AbseRtotal += abs(eR);
AbseGtotal += abs(eG);
AbseBtotal += abs(eB);
if (eR | eG | eB)
eCodes++;
eBits += abs(eR) + abs(eG) + abs(eB);
}
static void
setupLumaTables(void)
{
lumaRed = setupLuma(LumaRed);
lumaGreen = setupLuma(LumaGreen);
lumaBlue = setupLuma(LumaBlue);
D1 = 1.F/(2.F - 2.F*LumaBlue);
D2 = 1.F/(2.F - 2.F*LumaRed);
Yzero = V2Code(0, refBlackWhite[0], refBlackWhite[1], 255);
}
