tif_getimage.c

这是VCF框架的代码

	for (x = w; x-- > 0;) {
	    av = *a++;
	    rv = (*r++ * av) / 255;
	    gv = (*g++ * av) / 255;
	    bv = (*b++ * av) / 255;
	    *cp++ = PACK4(rv,gv,bv,av);
	}
	SKEW4(r, g, b, a, fromskew);
	cp += toskew;
    }
}

/*
 * 16-bit unpacked samples => RGB
 */
DECLARESepPutFunc(putRGBseparate16bittile)
{
    uint16 *wr = (uint16*) r;
    uint16 *wg = (uint16*) g;
    uint16 *wb = (uint16*) b;

    (void) img; (void) y; (void) a;
    while (h-- > 0) {
	for (x = 0; x < w; x++)
	    *cp++ = PACKW(*wr++, *wg++, *wb++);
	SKEW(wr, wg, wb, fromskew);
	cp += toskew;
    }
}

/*
 * 16-bit unpacked samples => RGBA w/ associated alpha
 */
DECLARESepPutFunc(putRGBAAseparate16bittile)
{
    uint16 *wr = (uint16*) r;
    uint16 *wg = (uint16*) g;
    uint16 *wb = (uint16*) b;
    uint16 *wa = (uint16*) a;

    (void) img; (void) y;
    while (h-- > 0) {
	for (x = 0; x < w; x++)
	    *cp++ = PACKW4(*wr++, *wg++, *wb++, *wa++);
	SKEW4(wr, wg, wb, wa, fromskew);
	cp += toskew;
    }
}

/*
 * 16-bit unpacked samples => RGBA w/ unassociated alpha
 */
DECLARESepPutFunc(putRGBUAseparate16bittile)
{
    uint16 *wr = (uint16*) r;
    uint16 *wg = (uint16*) g;
    uint16 *wb = (uint16*) b;
    uint16 *wa = (uint16*) a;

    (void) img; (void) y;
    while (h-- > 0) {
	uint32 r,g,b,a;
	/*
	 * We shift alpha down four bits just in case unsigned
	 * arithmetic doesn't handle the full range.
	 * We still have plenty of accuracy, since the output is 8 bits.
	 * So we have (r * 0xffff) * (a * 0xfff)) = r*a * (0xffff*0xfff)
	 * Since we want r*a * 0xff for eight bit output,
	 * we divide by (0xffff * 0xfff) / 0xff == 0x10eff.
	 */
	for (x = w; x-- > 0;) {
	    a = *wa++ >> 4; 
	    r = (*wr++ * a) / 0x10eff;
	    g = (*wg++ * a) / 0x10eff;
	    b = (*wb++ * a) / 0x10eff;
	    *cp++ = PACK4(r,g,b,a);
	}
	SKEW4(wr, wg, wb, wa, fromskew);
	cp += toskew;
    }
}

/*
 * YCbCr -> RGB conversion and packing routines.  The colorspace
 * conversion algorithm comes from the IJG v5a code; see below
 * for more information on how it works.
 */

#define	YCbCrtoRGB(dst, yc) {						\
    int Y = (yc);							\
    dst = PACK(								\
	clamptab[Y+Crrtab[Cr]],						\
	clamptab[Y + (int)((Cbgtab[Cb]+Crgtab[Cr])>>16)],		\
	clamptab[Y+Cbbtab[Cb]]);					\
}
#define	YCbCrSetup							\
    TIFFYCbCrToRGB* ycbcr = img->ycbcr;					\
    int* Crrtab = ycbcr->Cr_r_tab;					\
    int* Cbbtab = ycbcr->Cb_b_tab;					\
    int32* Crgtab = ycbcr->Cr_g_tab;					\
    int32* Cbgtab = ycbcr->Cb_g_tab;					\
    TIFFRGBValue* clamptab = ycbcr->clamptab

/*
 * 8-bit packed YCbCr samples => RGB 
 * This function is generic for different sampling sizes, 
 * and can handle blocks sizes that aren't multiples of the
 * sampling size.  However, it is substantially less optimized
 * than the specific sampling cases.  It is used as a fallback
 * for difficult blocks.
 */
#ifdef notdef
static void putcontig8bitYCbCrGenericTile( 
    TIFFRGBAImage* img, 
    uint32* cp, 
    uint32 x, uint32 y, 
    uint32 w, uint32 h, 
    int32 fromskew, int32 toskew, 
    u_char* pp,
    int h_group, 
    int v_group )

{
    YCbCrSetup;
    
    uint32* cp1 = cp+w+toskew;
    uint32* cp2 = cp1+w+toskew;
    uint32* cp3 = cp2+w+toskew;
    int32 incr = 3*w+4*toskew;
    int     Cb, Cr;
    int     group_size = v_group * h_group + 2;

    (void) y;
    fromskew = (fromskew * group_size) / h_group;

    for( yy = 0; yy < h; yy++ )
    {
        u_char *pp_line;
        int     y_line_group = yy / v_group;
        int     y_remainder = yy - y_line_group * v_group;

        pp_line = pp + v_line_group * 

        
        for( xx = 0; xx < w; xx++ )
        {
            Cb = pp
        }
    }
    for (; h >= 4; h -= 4) {
	x = w>>2;
	do {
	    Cb = pp[16];
	    Cr = pp[17];

	    YCbCrtoRGB(cp [0], pp[ 0]);
	    YCbCrtoRGB(cp [1], pp[ 1]);
	    YCbCrtoRGB(cp [2], pp[ 2]);
	    YCbCrtoRGB(cp [3], pp[ 3]);
	    YCbCrtoRGB(cp1[0], pp[ 4]);
	    YCbCrtoRGB(cp1[1], pp[ 5]);
	    YCbCrtoRGB(cp1[2], pp[ 6]);
	    YCbCrtoRGB(cp1[3], pp[ 7]);
	    YCbCrtoRGB(cp2[0], pp[ 8]);
	    YCbCrtoRGB(cp2[1], pp[ 9]);
	    YCbCrtoRGB(cp2[2], pp[10]);
	    YCbCrtoRGB(cp2[3], pp[11]);
	    YCbCrtoRGB(cp3[0], pp[12]);
	    YCbCrtoRGB(cp3[1], pp[13]);
	    YCbCrtoRGB(cp3[2], pp[14]);
	    YCbCrtoRGB(cp3[3], pp[15]);

	    cp += 4, cp1 += 4, cp2 += 4, cp3 += 4;
	    pp += 18;
	} while (--x);
	cp += incr, cp1 += incr, cp2 += incr, cp3 += incr;
	pp += fromskew;
    }
}
#endif

/*
 * 8-bit packed YCbCr samples w/ 4,4 subsampling => RGB
 */
DECLAREContigPutFunc(putcontig8bitYCbCr44tile)
{
    YCbCrSetup;
    uint32* cp1 = cp+w+toskew;
    uint32* cp2 = cp1+w+toskew;
    uint32* cp3 = cp2+w+toskew;
    int32 incr = 3*w+4*toskew;

    (void) y;
    /* adjust fromskew */
    fromskew = (fromskew * 18) / 4;
    if ((h & 3) == 0 && (w & 3) == 0) {				        
        for (; h >= 4; h -= 4) {
            x = w>>2;
            do {
                int Cb = pp[16];
                int Cr = pp[17];

                YCbCrtoRGB(cp [0], pp[ 0]);
                YCbCrtoRGB(cp [1], pp[ 1]);
                YCbCrtoRGB(cp [2], pp[ 2]);
                YCbCrtoRGB(cp [3], pp[ 3]);
                YCbCrtoRGB(cp1[0], pp[ 4]);
                YCbCrtoRGB(cp1[1], pp[ 5]);
                YCbCrtoRGB(cp1[2], pp[ 6]);
                YCbCrtoRGB(cp1[3], pp[ 7]);
                YCbCrtoRGB(cp2[0], pp[ 8]);
                YCbCrtoRGB(cp2[1], pp[ 9]);
                YCbCrtoRGB(cp2[2], pp[10]);
                YCbCrtoRGB(cp2[3], pp[11]);
                YCbCrtoRGB(cp3[0], pp[12]);
                YCbCrtoRGB(cp3[1], pp[13]);
                YCbCrtoRGB(cp3[2], pp[14]);
                YCbCrtoRGB(cp3[3], pp[15]);

                cp += 4, cp1 += 4, cp2 += 4, cp3 += 4;
                pp += 18;
            } while (--x);
            cp += incr, cp1 += incr, cp2 += incr, cp3 += incr;
            pp += fromskew;
        }
    } else {
        while (h > 0) {
            for (x = w; x > 0;) {
                int Cb = pp[16];
                int Cr = pp[17];
                switch (x) {
                default:
                    switch (h) {
                    default: YCbCrtoRGB(cp3[3], pp[15]); /* FALLTHROUGH */
                    case 3:  YCbCrtoRGB(cp2[3], pp[11]); /* FALLTHROUGH */
                    case 2:  YCbCrtoRGB(cp1[3], pp[ 7]); /* FALLTHROUGH */
                    case 1:  YCbCrtoRGB(cp [3], pp[ 3]); /* FALLTHROUGH */
                    }                                    /* FALLTHROUGH */
                case 3:
                    switch (h) {
                    default: YCbCrtoRGB(cp3[2], pp[14]); /* FALLTHROUGH */
                    case 3:  YCbCrtoRGB(cp2[2], pp[10]); /* FALLTHROUGH */
                    case 2:  YCbCrtoRGB(cp1[2], pp[ 6]); /* FALLTHROUGH */
                    case 1:  YCbCrtoRGB(cp [2], pp[ 2]); /* FALLTHROUGH */
                    }                                    /* FALLTHROUGH */
                case 2:
                    switch (h) {
                    default: YCbCrtoRGB(cp3[1], pp[13]); /* FALLTHROUGH */
                    case 3:  YCbCrtoRGB(cp2[1], pp[ 9]); /* FALLTHROUGH */
                    case 2:  YCbCrtoRGB(cp1[1], pp[ 5]); /* FALLTHROUGH */
                    case 1:  YCbCrtoRGB(cp [1], pp[ 1]); /* FALLTHROUGH */
                    }                                    /* FALLTHROUGH */
                case 1:
                    switch (h) {
                    default: YCbCrtoRGB(cp3[0], pp[12]); /* FALLTHROUGH */
                    case 3:  YCbCrtoRGB(cp2[0], pp[ 8]); /* FALLTHROUGH */
                    case 2:  YCbCrtoRGB(cp1[0], pp[ 4]); /* FALLTHROUGH */
                    case 1:  YCbCrtoRGB(cp [0], pp[ 0]); /* FALLTHROUGH */
                    }                                    /* FALLTHROUGH */
                }
                if (x < 4) {
                    cp += x; cp1 += x; cp2 += x; cp3 += x;
                    x = 0;
                }
                else {
                    cp += 4; cp1 += 4; cp2 += 4; cp3 += 4;
                    x -= 4;
                }
                pp += 18;
            }
            if (h <= 4)
                break;
            h -= 4;
            cp += incr, cp1 += incr, cp2 += incr, cp3 += incr;
            pp += fromskew;
        }
    }
}

/*
 * 8-bit packed YCbCr samples w/ 4,2 subsampling => RGB
 */
DECLAREContigPutFunc(putcontig8bitYCbCr42tile)
{
    YCbCrSetup;
    uint32* cp1 = cp+w+toskew;
    int32 incr = 2*toskew+w;

    (void) y;
    fromskew = (fromskew * 10) / 4;
    if ((h & 3) == 0 && (w & 1) == 0) {
        for (; h >= 2; h -= 2) {
            x = w>>2;
            do {
                int Cb = pp[8];
                int Cr = pp[9];
                
                YCbCrtoRGB(cp [0], pp[0]);
                YCbCrtoRGB(cp [1], pp[1]);
                YCbCrtoRGB(cp [2], pp[2]);
                YCbCrtoRGB(cp [3], pp[3]);
                YCbCrtoRGB(cp1[0], pp[4]);
                YCbCrtoRGB(cp1[1], pp[5]);
                YCbCrtoRGB(cp1[2], pp[6]);
                YCbCrtoRGB(cp1[3], pp[7]);
                
                cp += 4, cp1 += 4;
                pp += 10;
            } while (--x);
            cp += incr, cp1 += incr;
            pp += fromskew;
        }
    } else {
        while (h > 0) {
            for (x = w; x > 0;) {
                int Cb = pp[8];
                int Cr = pp[9];
                switch (x) {
                default:
                    switch (h) {
                    default: YCbCrtoRGB(cp1[3], pp[ 7]); /* FALLTHROUGH */
                    case 1:  YCbCrtoRGB(cp [3], pp[ 3]); /* FALLTHROUGH */
                    }                                    /* FALLTHROUGH */
                case 3:
                    switch (h) {
                    default: YCbCrtoRGB(cp1[2], pp[ 6]); /* FALLTHROUGH */
                    case 1:  YCbCrtoRGB(cp [2], pp[ 2]); /* FALLTHROUGH */
                    }                                    /* FALLTHROUGH */
                case 2:
                    switch (h) {
                    default: YCbCrtoRGB(cp1[1], pp[ 5]); /* FALLTHROUGH */
                    case 1:  YCbCrtoRGB(cp [1], pp[ 1]); /* FALLTHROUGH */
                    }                                    /* FALLTHROUGH */
                case 1:
                    switch (h) {
                    default: YCbCrtoRGB(cp1[0], pp[ 4]); /* FALLTHROUGH */
                    case 1:  YCbCrtoRGB(cp [0], pp[ 0]); /* FALLTHROUGH */
                    }                                    /* FALLTHROUGH */
                }
                if (x < 4) {
                    cp += x; cp1 += x;
                    x = 0;
                }
                else {
                    cp += 4; cp1 += 4;
                    x -= 4;
                }
                pp += 10;
            }
            if (h <= 2)
                break;
            h -= 2;
            cp += incr, cp1 += incr;
            pp += fromskew;
        }
    }
}

/*
 * 8-bit packed YCbCr samples w/ 4,1 subsampling => RGB
 */
DECLAREContigPutFunc(putcontig8bitYCbCr41tile)
{
    YCbCrSetup;

    (void) y;
    /* XXX adjust fromskew */
    do {
	x = w>>2;
	do {
	    int Cb = pp[4];
	    int Cr = pp[5];

	    YCbCrtoRGB(cp [0], pp[0]);
	    YCbCrtoRGB(cp [1], pp[1]);
	    YCbCrtoRGB(cp [2], pp[2]);
	    YCbCrtoRGB(cp [3], pp[3]);

	    cp += 4;
	    pp += 6;
	} while (--x);

        if( (w&3) != 0 )
        {
	    int Cb = pp[4];
	    int Cr = pp[5];

            switch( (w&3) ) {
              case 3: YCbCrtoRGB(cp [2], pp[2]);
              case 2: YCbCrtoRGB(cp [1], pp[1]);
              case 1: YCbCrtoRGB(cp [0], pp[0]);
              case 0: break;
            }

            cp += (w&3);
            pp += 6;
        }

	cp += toskew;
	pp += fromskew;
    } while (--h);

}

/*
 * 8-bit packed YCbCr samples w/ 2,2 subsampling => RGB
 */
DECLAREContigPutFunc(putcontig8bitYCbCr22tile)
{
    YCbCrSetup;
    uint32* cp1 = cp+w+toskew;
    int32 incr = 2*toskew+w;

    (void) y;
    fromskew = (fromskew * 6) / 2;
    if ((h & 1) == 0 && (w & 1) == 0) {
        for (; h >= 2; h -= 2) {
            x = w>>1;
            do {
                int Cb = pp[4];
                int Cr = pp[5];

                YCbCrtoRGB(cp [0], pp[0]);
                YCbCrtoRGB(cp [1], pp[1]);
                YCbCrtoRGB(cp1[0], pp[2]);
                YCbCrtoRGB(cp1[1], pp[3]);

                cp += 2, cp1 += 2;
                pp += 6;
            } while (--x);
            cp += incr, cp1 += incr;
            pp += fromskew;
        }
    } else {
        while (h > 0) {
            for (x = w; x > 0;) {
                int Cb = pp[4];
                int Cr = pp[5];
                switch (x) {
                default:
                    switch (h) {
                    default: YCbCrtoRGB(cp1[1], pp[ 3]); /* FALLTHROUGH */
                    case 1:  YCbCrtoRGB(cp [1], pp[ 1]); /* FALLTHROUGH */
                    }                                    /* FALLTHROUGH */
                case 1:
                    switch (h) {
                    default: YCbCrtoRGB(cp1[0], pp[ 2]); /* FALLTHROUGH */
                    case 1:  YCbCrtoRGB(cp [0], pp[ 0]); /* FALLTHROUGH */
                    }                                    /* FALLTHROUGH */
                }
                if (x < 2) {
                    cp += x; cp1 += x;
                    x = 0;
                }
                else {
                    cp += 2; cp1 += 2;
                    x -= 2;
                }
                pp += 6;
            }
            if (h <= 2)
                break;
            h -= 2;
            cp += incr, cp1 += incr;
            pp += fromskew;
        }
    }
}

/*
 * 8-bit packed YCbCr samples w/ 2,1 subsampling => RGB
 */
DECLAREContigPutFunc(putcontig8bitYCbCr21tile)
{
    YCbCrSetup;

    (void) y;
    fromskew = (fromskew * 4) / 2;
    do {
	x = w>>1;
	do {
	    int Cb = pp[2];
	    int Cr = pp[3];

	    YCbCrtoRGB(cp[0], pp[0]); 
	    YCbCrtoRGB(cp[1], pp[1]);

	    cp += 2;
	    pp += 4;
	} while (--x);

        if( (w&1) != 0 )
        {
	    int Cb = pp[2];
	    int Cr = pp[3];
            
            YCbCrtoRGB(cp [0], pp[0]);

	    cp += 1;
	    pp += 4;
        }

	cp += toskew;
	pp += fromskew;
    } while (--h);
}

/*
 * 8-bit packed YCbCr samples w/ no subsampling => RGB
 */
DECLAREContigPutFunc(putcontig8bitYCbCr11tile)
{
    YCbCrSetup;

    (void) y;
    fromskew *= 3;
    do {
        x = w; /* was x = w>>1; patched 2000/09/25 [e-mail] */ 
	do {
	    int Cb = pp[1];
	    int Cr = pp[2];

	    YCbCrtoRGB(*cp++, pp[0]);

	    pp += 3;
	} while (--x);
	cp += toskew;
	pp += fromskew;
    } while (--h);
}
#undef	YCbCrSetup
#undef	YCbCrtoRGB

#define	LumaRed			coeffs[0]
#define	LumaGreen		coeffs[1]
#define	LumaBlue		coeffs[2]
#define	SHIFT			16
#define	FIX(x)			((int32)((x) * (1L<<SHIFT) + 0.5))
#define	ONE_HALF		((int32)(1<<(SHIFT-1)))

/*
 * Initialize the YCbCr->RGB conversion tables.  The conversion
 * is done according to the 6.0 spec:
 *
 *    R = Y + Cr*(2 - 2*LumaRed)
 *    B = Y + Cb*(2 - 2*LumaBlue)
 *    G =   Y
 *        - LumaBlue*Cb*(2-2*LumaBlue)/LumaGreen
 *        - LumaRed*Cr*(2-2*LumaRed)/LumaGreen
 *
 * To avoid floating point arithmetic the fractional constants that
 * come out of the equations are represented as fixed point values
 * in the range 0...2^16.  We also eliminate multiplications by
 * pre-calculating possible values indexed by Cb and Cr (this code
 * assumes conversion is being done for 8-bit samples).
 */
static void
TIFFYCbCrToRGBInit(TIFFYCbCrToRGB* ycbcr, TIFF* tif)
{
    TIFFRGBValue* clamptab;
    float* coeffs;
    int i;

    clamptab = (TIFFRGBValue*)(
	(tidata_t) ycbcr+TIFFroundup(sizeof (TIFFYCbCrToRGB), sizeof (long)));
    _TIFFmemset(clamptab, 0, 256);		/* v < 0 => 0 */
    ycbcr->clamptab = (clamptab += 256);
    for (i = 0; i < 256; i++)
	clamptab[i] = i;
    _TIFFmemset(clamptab+256, 255, 2*256);	/* v > 255 => 255 */
    TIFFGetFieldDefaulted(tif, TIFFTAG_YCBCRCOEFFICIENTS, &coeffs);
    _TIFFmemcpy(ycbcr->coeffs, coeffs, 3*sizeof (float));
    { float f1 = 2-2*LumaRed;		int32 D1 = FIX(f1);
      float f2 = LumaRed*f1/LumaGreen;	int32 D2 = -FIX(f2);