tif_getimage.c

支持各种栅格图像和矢量图像读取的库

	static char module[] = "initCIELabConversion";

	float   *whitePoint;
	float   refWhite[3];

	if (!img->cielab) {
		img->cielab = (TIFFCIELabToRGB *)
			_TIFFmalloc(sizeof(TIFFCIELabToRGB));
		if (!img->cielab) {
			TIFFErrorExt(img->tif->tif_clientdata, module,
			    "No space for CIE L*a*b*->RGB conversion state.");
			return NULL;
		}
	}

	TIFFGetFieldDefaulted(img->tif, TIFFTAG_WHITEPOINT, &whitePoint);
	refWhite[1] = 100.0F;
	refWhite[0] = whitePoint[0] / whitePoint[1] * refWhite[1];
	refWhite[2] = (1.0F - whitePoint[0] - whitePoint[1])
		      / whitePoint[1] * refWhite[1];
	if (TIFFCIELabToRGBInit(img->cielab, &display_sRGB, refWhite) < 0) {
		TIFFErrorExt(img->tif->tif_clientdata, module,
		    "Failed to initialize CIE L*a*b*->RGB conversion state.");
		_TIFFfree(img->cielab);
		return NULL;
	}

	return putcontig8bitCIELab;
}

/*
 * Greyscale images with less than 8 bits/sample are handled
 * with a table to avoid lots of shifts and masks.  The table
 * is setup so that put*bwtile (below) can retrieve 8/bitspersample
 * pixel values simply by indexing into the table with one
 * number.
 */
static int
makebwmap(TIFFRGBAImage* img)
{
    TIFFRGBValue* Map = img->Map;
    int bitspersample = img->bitspersample;
    int nsamples = 8 / bitspersample;
    int i;
    uint32* p;

    if( nsamples == 0 )
        nsamples = 1;

    img->BWmap = (uint32**) _TIFFmalloc(
	256*sizeof (uint32 *)+(256*nsamples*sizeof(uint32)));
    if (img->BWmap == NULL) {
		TIFFErrorExt(img->tif->tif_clientdata, TIFFFileName(img->tif), "No space for B&W mapping table");
		return (0);
    }
    p = (uint32*)(img->BWmap + 256);
    for (i = 0; i < 256; i++) {
	TIFFRGBValue c;
	img->BWmap[i] = p;
	switch (bitspersample) {
#define	GREY(x)	c = Map[x]; *p++ = PACK(c,c,c);
	case 1:
	    GREY(i>>7);
	    GREY((i>>6)&1);
	    GREY((i>>5)&1);
	    GREY((i>>4)&1);
	    GREY((i>>3)&1);
	    GREY((i>>2)&1);
	    GREY((i>>1)&1);
	    GREY(i&1);
	    break;
	case 2:
	    GREY(i>>6);
	    GREY((i>>4)&3);
	    GREY((i>>2)&3);
	    GREY(i&3);
	    break;
	case 4:
	    GREY(i>>4);
	    GREY(i&0xf);
	    break;
	case 8:
        case 16:
	    GREY(i);
	    break;
	}
#undef	GREY
    }
    return (1);
}

/*
 * Construct a mapping table to convert from the range
 * of the data samples to [0,255] --for display.  This
 * process also handles inverting B&W images when needed.
 */ 
static int
setupMap(TIFFRGBAImage* img)
{
    int32 x, range;

    range = (int32)((1L<<img->bitspersample)-1);
    
    /* treat 16 bit the same as eight bit */
    if( img->bitspersample == 16 )
        range = (int32) 255;

    img->Map = (TIFFRGBValue*) _TIFFmalloc((range+1) * sizeof (TIFFRGBValue));
    if (img->Map == NULL) {
		TIFFErrorExt(img->tif->tif_clientdata, TIFFFileName(img->tif),
			"No space for photometric conversion table");
		return (0);
    }
    if (img->photometric == PHOTOMETRIC_MINISWHITE) {
	for (x = 0; x <= range; x++)
	    img->Map[x] = (TIFFRGBValue) (((range - x) * 255) / range);
    } else {
	for (x = 0; x <= range; x++)
	    img->Map[x] = (TIFFRGBValue) ((x * 255) / range);
    }
    if (img->bitspersample <= 16 &&
	(img->photometric == PHOTOMETRIC_MINISBLACK ||
	 img->photometric == PHOTOMETRIC_MINISWHITE)) {
	/*
	 * Use photometric mapping table to construct
	 * unpacking tables for samples <= 8 bits.
	 */
	if (!makebwmap(img))
	    return (0);
	/* no longer need Map, free it */
	_TIFFfree(img->Map), img->Map = NULL;
    }
    return (1);
}

static int
checkcmap(TIFFRGBAImage* img)
{
    uint16* r = img->redcmap;
    uint16* g = img->greencmap;
    uint16* b = img->bluecmap;
    long n = 1L<<img->bitspersample;

    while (n-- > 0)
	if (*r++ >= 256 || *g++ >= 256 || *b++ >= 256)
	    return (16);
    return (8);
}

static void
cvtcmap(TIFFRGBAImage* img)
{
    uint16* r = img->redcmap;
    uint16* g = img->greencmap;
    uint16* b = img->bluecmap;
    long i;

    for (i = (1L<<img->bitspersample)-1; i >= 0; i--) {
#define	CVT(x)		((uint16)((x)>>8))
	r[i] = CVT(r[i]);
	g[i] = CVT(g[i]);
	b[i] = CVT(b[i]);
#undef	CVT
    }
}

/*
 * Palette images with <= 8 bits/sample are handled
 * with a table to avoid lots of shifts and masks.  The table
 * is setup so that put*cmaptile (below) can retrieve 8/bitspersample
 * pixel values simply by indexing into the table with one
 * number.
 */
static int
makecmap(TIFFRGBAImage* img)
{
    int bitspersample = img->bitspersample;
    int nsamples = 8 / bitspersample;
    uint16* r = img->redcmap;
    uint16* g = img->greencmap;
    uint16* b = img->bluecmap;
    uint32 *p;
    int i;

    img->PALmap = (uint32**) _TIFFmalloc(
	256*sizeof (uint32 *)+(256*nsamples*sizeof(uint32)));
    if (img->PALmap == NULL) {
		TIFFErrorExt(img->tif->tif_clientdata, TIFFFileName(img->tif), "No space for Palette mapping table");
		return (0);
	}
    p = (uint32*)(img->PALmap + 256);
    for (i = 0; i < 256; i++) {
	TIFFRGBValue c;
	img->PALmap[i] = p;
#define	CMAP(x)	c = (TIFFRGBValue) x; *p++ = PACK(r[c]&0xff, g[c]&0xff, b[c]&0xff);
	switch (bitspersample) {
	case 1:
	    CMAP(i>>7);
	    CMAP((i>>6)&1);
	    CMAP((i>>5)&1);
	    CMAP((i>>4)&1);
	    CMAP((i>>3)&1);
	    CMAP((i>>2)&1);
	    CMAP((i>>1)&1);
	    CMAP(i&1);
	    break;
	case 2:
	    CMAP(i>>6);
	    CMAP((i>>4)&3);
	    CMAP((i>>2)&3);
	    CMAP(i&3);
	    break;
	case 4:
	    CMAP(i>>4);
	    CMAP(i&0xf);
	    break;
	case 8:
	    CMAP(i);
	    break;
	}
#undef CMAP
    }
    return (1);
}

/* 
 * Construct any mapping table used
 * by the associated put routine.
 */
static int
buildMap(TIFFRGBAImage* img)
{
    switch (img->photometric) {
    case PHOTOMETRIC_RGB:
    case PHOTOMETRIC_YCBCR:
    case PHOTOMETRIC_SEPARATED:
	if (img->bitspersample == 8)
	    break;
	/* fall thru... */
    case PHOTOMETRIC_MINISBLACK:
    case PHOTOMETRIC_MINISWHITE:
	if (!setupMap(img))
	    return (0);
	break;
    case PHOTOMETRIC_PALETTE:
	/*
	 * Convert 16-bit colormap to 8-bit (unless it looks
	 * like an old-style 8-bit colormap).
	 */
	if (checkcmap(img) == 16)
	    cvtcmap(img);
	else
	    TIFFWarningExt(img->tif->tif_clientdata, TIFFFileName(img->tif), "Assuming 8-bit colormap");
	/*
	 * Use mapping table and colormap to construct
	 * unpacking tables for samples < 8 bits.
	 */
	if (img->bitspersample <= 8 && !makecmap(img))
	    return (0);
	break;
    }
    return (1);
}

/*
 * Select the appropriate conversion routine for packed data.
 */
static int
PickContigCase(TIFFRGBAImage* img)
{
	img->get = TIFFIsTiled(img->tif) ? gtTileContig : gtStripContig;
	img->put.contig = NULL;
	switch (img->photometric) {
		case PHOTOMETRIC_RGB:
			switch (img->bitspersample) {
				case 8:
					if (img->alpha == EXTRASAMPLE_ASSOCALPHA)
						img->put.contig = putRGBAAcontig8bittile;
					else if (img->alpha == EXTRASAMPLE_UNASSALPHA)
					{
						if (BuildMapUaToAa(img))
							img->put.contig = putRGBUAcontig8bittile;
					}
					else
						img->put.contig = putRGBcontig8bittile;
					break;
				case 16:
					if (img->alpha == EXTRASAMPLE_ASSOCALPHA)
					{
						if (BuildMapBitdepth16To8(img))
							img->put.contig = putRGBAAcontig16bittile;
					}
					else if (img->alpha == EXTRASAMPLE_UNASSALPHA)
					{
						if (BuildMapBitdepth16To8(img) &&
						    BuildMapUaToAa(img))
							img->put.contig = putRGBUAcontig16bittile;
					}
					else
					{
						if (BuildMapBitdepth16To8(img))
							img->put.contig = putRGBcontig16bittile;
					}
					break;
			}
			break;
		case PHOTOMETRIC_SEPARATED:
			if (buildMap(img)) {
				if (img->bitspersample == 8) {
					if (!img->Map)
						img->put.contig = putRGBcontig8bitCMYKtile;
					else
						img->put.contig = putRGBcontig8bitCMYKMaptile;
				}
			}
			break;
		case PHOTOMETRIC_PALETTE:
			if (buildMap(img)) {
				switch (img->bitspersample) {
					case 8:
						img->put.contig = put8bitcmaptile;
						break;
					case 4:
						img->put.contig = put4bitcmaptile;
						break;
					case 2:
						img->put.contig = put2bitcmaptile;
						break;
					case 1:
						img->put.contig = put1bitcmaptile;
						break;
				}
			}
			break;
		case PHOTOMETRIC_MINISWHITE:
		case PHOTOMETRIC_MINISBLACK:
			if (buildMap(img)) {
				switch (img->bitspersample) {
					case 16:
						img->put.contig = put16bitbwtile;
						break;
					case 8:
						img->put.contig = putgreytile;
						break;
					case 4:
						img->put.contig = put4bitbwtile;
						break;
					case 2:
						img->put.contig = put2bitbwtile;
						break;
					case 1:
						img->put.contig = put1bitbwtile;
						break;
				}
			}
			break;
		case PHOTOMETRIC_YCBCR:
			if (img->bitspersample == 8)
			{
				if (initYCbCrConversion(img)!=0)
				{
					uint16 hs, vs;
					/*
					 * The 6.0 spec says that subsampling must be
					 * one of 1, 2, or 4, and that vertical subsampling
					 * must always be <= horizontal subsampling; so
					 * there are only a few possibilities and we just
					 * enumerate the cases.
					 * Joris: added support for the [1,2] case, nonetheless, to accomodate
					 * some OJPEG files
					 */
					TIFFGetFieldDefaulted(img->tif, TIFFTAG_YCBCRSUBSAMPLING, &hs, &vs);
					switch ((hs<<4)|vs) {
						case 0x44:
							img->put.contig = putcontig8bitYCbCr44tile;
							break;
						case 0x42:
							img->put.contig = putcontig8bitYCbCr42tile;
							break;
						case 0x41:
							img->put.contig = putcontig8bitYCbCr41tile;
							break;
						case 0x22:
							img->put.contig = putcontig8bitYCbCr22tile;
							break;
						case 0x21:
							img->put.contig = putcontig8bitYCbCr21tile;
							break;
						case 0x12:
							img->put.contig = putcontig8bitYCbCr12tile;
							break;
						case 0x11:
							img->put.contig = putcontig8bitYCbCr11tile;
							break;
					}
				}
			}
			break;
		case PHOTOMETRIC_CIELAB:
			if (buildMap(img)) {
				if (img->bitspersample == 8)
					img->put.contig = initCIELabConversion(img);
				break;
			}
	}
	return ((img->get!=NULL) && (img->put.contig!=NULL));
}

/*
 * Select the appropriate conversion routine for unpacked data.
 *
 * NB: we assume that unpacked single channel data is directed
 *	 to the "packed routines.
 */
static int
PickSeparateCase(TIFFRGBAImage* img)
{
	img->get = TIFFIsTiled(img->tif) ? gtTileSeparate : gtStripSeparate;
	img->put.separate = NULL;
	switch (img->photometric) {
		case PHOTOMETRIC_RGB:
			switch (img->bitspersample) {
				case 8:
					if (img->alpha == EXTRASAMPLE_ASSOCALPHA)
						img->put.separate = putRGBAAseparate8bittile;
					else if (img->alpha == EXTRASAMPLE_UNASSALPHA)
					{
						if (BuildMapUaToAa(img))
							img->put.separate = putRGBUAseparate8bittile;
					}
					else
						img->put.separate = putRGBseparate8bittile;
					break;
				case 16:
					if (img->alpha == EXTRASAMPLE_ASSOCALPHA)
					{
						if (BuildMapBitdepth16To8(img))
							img->put.separate = putRGBAAseparate16bittile;
					}
					else if (img->alpha == EXTRASAMPLE_UNASSALPHA)
					{
						if (BuildMapBitdepth16To8(img) &&
						    BuildMapUaToAa(img))
							img->put.separate = putRGBUAseparate16bittile;
					}
					else
					{
						if (BuildMapBitdepth16To8(img))
							img->put.separate = putRGBseparate16bittile;
					}
					break;
			}
			break;
		case PHOTOMETRIC_YCBCR:
			if ((img->bitspersample==8) && (img->samplesperpixel==3))
			{
				if (initYCbCrConversion(img)!=0)
				{
					uint16 hs, vs;
					TIFFGetFieldDefaulted(img->tif, TIFFTAG_YCBCRSUBSAMPLING, &hs, &vs);
					switch ((hs<<4)|vs) {
						case 0x11:
							img->put.separate = putseparate8bitYCbCr11tile;
							break;
						/* TODO: add other cases here */
					}
				}
			}
			break;
	}
	return ((img->get!=NULL) && (img->put.separate!=NULL));
}

static int
BuildMapUaToAa(TIFFRGBAImage* img)
{
	static const char module[]="BuildMapUaToAa";
	uint8* m;
	uint16 na,nv;
	assert(img->UaToAa==NULL);
	img->UaToAa=_TIFFmalloc(65536);
	if (img->UaToAa==NULL)
	{
		TIFFErrorExt(img->tif,module,"Out of memory");
		return(0);
	}
	m=img->UaToAa;
	for (na=0; na<256; na++)
	{
		for (nv=0; nv<256; nv++)
			*m++=(nv*na+127)/255;
	}
	return(1);
}

static int
BuildMapBitdepth16To8(TIFFRGBAImage* img)
{
	static const char module[]="BuildMapBitdepth16To8";
	uint8* m;
	uint32 n;
	assert(img->Bitdepth16To8==NULL);
	img->Bitdepth16To8=_TIFFmalloc(65536);
	if (img->Bitdepth16To8==NULL)
	{
		TIFFErrorExt(img->tif,module,"Out of memory");
		return(0);
	}
	m=img->Bitdepth16To8;
	for (n=0; n<65536; n++)
		*m++=(n+128)/257;
	return(1);
}


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