thumbnail.c

tiff文件开发库

	    return (0);
    }
    return (1);
}

static	uint16	photometric;		/* current photometric of raster */
static	uint16	filterWidth;		/* filter width in pixels */
static	uint16	stepSrcWidth;		/* src image stepping width */
static	uint16	stepDstWidth;		/* dest stepping width */
static	uint8* src0;			/* horizontal bit stepping (start) */
static	uint8* src1;			/* horizontal bit stepping (middle) */
static	uint8* src2;			/* horizontal bit stepping (end) */
static	uint16* rowoff;			/* row offset for stepping */
static	uint8 cmap[256];		/* colormap indexes */
static	uint8 bits[256];		/* count of bits set */

static void
setupBitsTables()
{
    int i;
    for (i = 0; i < 256; i++) {
	int n = 0;
	if (i&0x01) n++;
	if (i&0x02) n++;
	if (i&0x04) n++;
	if (i&0x08) n++;
	if (i&0x10) n++;
	if (i&0x20) n++;
	if (i&0x40) n++;
	if (i&0x80) n++;
	bits[i] = n;
    }
}

static int clamp(float v, int low, int high)
    { return (v < low ? low : v > high ? high : (int)v); }

#ifndef M_E
#define M_E		2.7182818284590452354
#endif

static void
expFill(float pct[], uint32 p, uint32 n)
{
    uint32 i;
    uint32 c = (p * n) / 100;
    for (i = 1; i < c; i++)
	pct[i] = 1-exp(i/((double)(n-1)))/ M_E;
    for (; i < n; i++)
	pct[i] = 0.;
}

static void
setupCmap()
{
    float pct[256];			/* known to be large enough */
    uint32 i;
    pct[0] = 1;				/* force white */
    switch (contrast) {
    case EXP50: expFill(pct, 50, 256); break;
    case EXP60:	expFill(pct, 60, 256); break;
    case EXP70:	expFill(pct, 70, 256); break;
    case EXP80:	expFill(pct, 80, 256); break;
    case EXP90:	expFill(pct, 90, 256); break;
    case EXP:	expFill(pct, 100, 256); break;
    case LINEAR:
	for (i = 1; i < 256; i++)
	    pct[i] = 1-((float)i)/(256-1);
	break;
    }
    switch (photometric) {
    case PHOTOMETRIC_MINISWHITE:
	for (i = 0; i < 256; i++)
	    cmap[i] = clamp(255*pct[(256-1)-i], 0, 255);
	break;
    case PHOTOMETRIC_MINISBLACK:
	for (i = 0; i < 256; i++)
	    cmap[i] = clamp(255*pct[i], 0, 255);
	break;
    }
}

static void
initScale()
{
    src0 = (uint8*) _TIFFmalloc(sizeof (uint8) * tnw);
    src1 = (uint8*) _TIFFmalloc(sizeof (uint8) * tnw);
    src2 = (uint8*) _TIFFmalloc(sizeof (uint8) * tnw);
    rowoff = (uint16*) _TIFFmalloc(sizeof (uint16) * tnw);
    filterWidth = 0;
    stepDstWidth = stepSrcWidth = 0;
    setupBitsTables();
}

/*
 * Calculate the horizontal accumulation parameteres
 * according to the widths of the src and dst images.
 */
static void
setupStepTables(uint16 sw)
{
    if (stepSrcWidth != sw || stepDstWidth != tnw) {
	int step = sw;
	int limit = tnw;
	int err = 0;
	uint32 sx = 0;
	uint32 x;
	int fw;
	uint8 b;
	for (x = 0; x < tnw; x++) {
	    uint32 sx0 = sx;
	    err += step;
	    while (err >= limit) {
		err -= limit;
		sx++;
	    }
	    rowoff[x] = sx0 >> 3;
	    fw = sx - sx0;		/* width */
	    b = (fw < 8) ? 0xff<<(8-fw) : 0xff;
	    src0[x] = b >> (sx0&7);
	    fw -= 8 - (sx0&7);
	    if (fw < 0)
		fw = 0;
	    src1[x] = fw >> 3;
	    fw -= (fw>>3)<<3;
	    src2[x] = 0xff << (8-fw);
	}
	stepSrcWidth = sw;
	stepDstWidth = tnw;
    }
}

static void
setrow(uint8* row, int nrows, const uint8* rows[])
{
    uint32 x;
    uint32 area = nrows * filterWidth;
    for (x = 0; x < tnw; x++) {
	uint32 mask0 = src0[x];
	uint32 fw = src1[x];
	uint32 mask1 = src1[x];
	uint32 off = rowoff[x];
	uint32 acc = 0;
	uint32 y, i;
	for (y = 0; y < nrows; y++) {
	    const uint8* src = rows[y] + off;
	    acc += bits[*src++ & mask0];
	    switch (fw) {
	    default:
		for (i = fw; i > 8; i--)
		    acc += bits[*src++];
		/* fall thru... */
	    case 8: acc += bits[*src++];
	    case 7: acc += bits[*src++];
	    case 6: acc += bits[*src++];
	    case 5: acc += bits[*src++];
	    case 4: acc += bits[*src++];
	    case 3: acc += bits[*src++];
	    case 2: acc += bits[*src++];
	    case 1: acc += bits[*src++];
	    case 0: break;
	    }
	    acc += bits[*src & mask1];
	}
	*row++ = cmap[(255*acc)/area];
    }
}

/*
 * Install the specified image.  The
 * image is resized to fit the display page using
 * a box filter.  The resultant pixels are mapped
 * with a user-selectable contrast curve.
 */
static void
setImage1(const uint8* br, uint32 rw, uint32 rh)
{
    int step = rh;
    int limit = tnh;
    int err = 0;
    int bpr = howmany(rw,8);
    uint32 sy = 0;
    uint8* row = thumbnail;
    uint32 dy;
    for (dy = 0; dy < tnh; dy++) {
	const uint8* rows[256];
	int nrows = 1;
	rows[0] = br + bpr*sy;
	err += step;
	while (err >= limit) {
	    err -= limit;
	    sy++;
	    if (err >= limit)
		rows[nrows++] = br + bpr*sy;
	}
	setrow(row, nrows, rows);
	row += tnw;
    }
}

static void
setImage(const uint8* br, uint32 rw, uint32 rh)
{
    filterWidth = (uint16) ceil((double) rw / (double) tnw);
    setupStepTables(rw);
    setImage1(br, rw, rh);
}

static int
generateThumbnail(TIFF* in, TIFF* out)
{
    unsigned char* raster;
    unsigned char* rp;
    uint32 sw, sh, rps;
    uint16 bps, spp;
    tsize_t rowsize, rastersize;
    tstrip_t s, ns = TIFFNumberOfStrips(in);
    uint32 diroff[1];

    TIFFGetField(in, TIFFTAG_IMAGEWIDTH, &sw);
    TIFFGetField(in, TIFFTAG_IMAGELENGTH, &sh);
    TIFFGetFieldDefaulted(in, TIFFTAG_BITSPERSAMPLE, &bps);
    TIFFGetFieldDefaulted(in, TIFFTAG_SAMPLESPERPIXEL, &spp);
    TIFFGetFieldDefaulted(in, TIFFTAG_ROWSPERSTRIP, &rps);
    if (spp != 1 || bps != 1)
	return (0);
    rowsize = TIFFScanlineSize(in);
    rastersize = sh * rowsize;
    raster = (unsigned char*)_TIFFmalloc(rastersize);
    rp = raster;
    for (s = 0; s < ns; s++) {
	(void) TIFFReadEncodedStrip(in, s, rp, -1);
	rp += rps * rowsize;
    }
    TIFFGetField(in, TIFFTAG_PHOTOMETRIC, &photometric);
    setupCmap();
    setImage(raster, sw, sh);
    _TIFFfree(raster);

    TIFFSetField(out, TIFFTAG_SUBFILETYPE, FILETYPE_REDUCEDIMAGE);
    TIFFSetField(out, TIFFTAG_IMAGEWIDTH, (uint32) tnw);
    TIFFSetField(out, TIFFTAG_IMAGELENGTH, (uint32) tnh);
    TIFFSetField(out, TIFFTAG_BITSPERSAMPLE, (uint16) 8);
    TIFFSetField(out, TIFFTAG_SAMPLESPERPIXEL, (uint16) 1);
    TIFFSetField(out, TIFFTAG_COMPRESSION, COMPRESSION_PACKBITS);
    TIFFSetField(out, TIFFTAG_PHOTOMETRIC, PHOTOMETRIC_MINISWHITE);
    TIFFSetField(out, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);
    TIFFSetField(out, TIFFTAG_ORIENTATION, ORIENTATION_TOPLEFT);
    cpTag(in, out, TIFFTAG_SOFTWARE,		(uint16) -1, TIFF_ASCII);
    cpTag(in, out, TIFFTAG_IMAGEDESCRIPTION,	(uint16) -1, TIFF_ASCII);
    cpTag(in, out, TIFFTAG_DATETIME,		(uint16) -1, TIFF_ASCII);
    cpTag(in, out, TIFFTAG_HOSTCOMPUTER,	(uint16) -1, TIFF_ASCII);
    diroff[0] = 0;
    TIFFSetField(out, TIFFTAG_SUBIFD, 1, diroff);
    return (TIFFWriteEncodedStrip(out, 0, thumbnail, tnw*tnh) != -1 &&
            TIFFWriteDirectory(out) != -1);
}

char* stuff[] = {
"usage: thumbnail [options] input.tif output.tif",
"where options are:",
" -h #		specify thumbnail image height (default is 274)",
" -w #		specify thumbnail image width (default is 216)",
"",
" -c linear	use linear contrast curve",
" -c exp50	use 50% exponential contrast curve",
" -c exp60	use 60% exponential contrast curve",
" -c exp70	use 70% exponential contrast curve",
" -c exp80	use 80% exponential contrast curve",
" -c exp90	use 90% exponential contrast curve",
" -c exp		use pure exponential contrast curve",
NULL
};

static void
usage(void)
{
	char buf[BUFSIZ];
	int i;

	setbuf(stderr, buf);
        fprintf(stderr, "%s\n\n", TIFFGetVersion());
	for (i = 0; stuff[i] != NULL; i++)
		fprintf(stderr, "%s\n", stuff[i]);
	exit(-1);
}