tif_aux.c

一个国人自己实现图像库的程序（有参考价值）

/* $Header: /cvsroot/osrs/libtiff/libtiff/tif_aux.c,v 1.3 2000/03/03 15:22:00 warmerda Exp $ */

/*
 * Copyright (c) 1991-1997 Sam Leffler
 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and 
 * its documentation for any purpose is hereby granted without fee, provided
 * that (i) the above copyright notices and this permission notice appear in
 * all copies of the software and related documentation, and (ii) the names of
 * Sam Leffler and Silicon Graphics may not be used in any advertising or
 * publicity relating to the software without the specific, prior written
 * permission of Sam Leffler and Silicon Graphics.
 * 
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
 * 
 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF 
 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
 * OF THIS SOFTWARE.
 */

/*
 * TIFF Library.
 *
 * Auxiliary Support Routines.
 */
#include "tiffiop.h"

#ifdef COLORIMETRY_SUPPORT
#include <math.h>

static void
TIFFDefaultTransferFunction(TIFFDirectory* td)
{
	uint16 **tf = td->td_transferfunction;
	long i, n = 1<<td->td_bitspersample;

	tf[0] = (uint16 *)_TIFFmalloc(n * sizeof (uint16));
	tf[0][0] = 0;
	for (i = 1; i < n; i++) {
		double t = (double)i/((double) n-1.);
		tf[0][i] = (uint16)floor(65535.*pow(t, 2.2) + .5);
	}
	if (td->td_samplesperpixel - td->td_extrasamples > 1) {
		tf[1] = (uint16 *)_TIFFmalloc(n * sizeof (uint16));
		_TIFFmemcpy(tf[1], tf[0], n * sizeof (uint16));
		tf[2] = (uint16 *)_TIFFmalloc(n * sizeof (uint16));
		_TIFFmemcpy(tf[2], tf[0], n * sizeof (uint16));
	}
}

static void
TIFFDefaultRefBlackWhite(TIFFDirectory* td)
{
	int i;

	td->td_refblackwhite = (float *)_TIFFmalloc(6*sizeof (float));
	for (i = 0; i < 3; i++) {
	    td->td_refblackwhite[2*i+0] = 0;
	    td->td_refblackwhite[2*i+1] = (float)((1L<<td->td_bitspersample)-1L);
	}
}
#endif

/*
 * Like TIFFGetField, but return any default
 * value if the tag is not present in the directory.
 *
 * NB:	We use the value in the directory, rather than
 *	explcit values so that defaults exist only one
 *	place in the library -- in TIFFDefaultDirectory.
 */
int
TIFFVGetFieldDefaulted(TIFF* tif, ttag_t tag, va_list ap)
{
	TIFFDirectory *td = &tif->tif_dir;

	if (TIFFVGetField(tif, tag, ap))
		return (1);
	switch (tag) {
	case TIFFTAG_SUBFILETYPE:
		*va_arg(ap, uint32 *) = td->td_subfiletype;
		return (1);
	case TIFFTAG_BITSPERSAMPLE:
		*va_arg(ap, uint16 *) = td->td_bitspersample;
		return (1);
	case TIFFTAG_THRESHHOLDING:
		*va_arg(ap, uint16 *) = td->td_threshholding;
		return (1);
	case TIFFTAG_FILLORDER:
		*va_arg(ap, uint16 *) = td->td_fillorder;
		return (1);
	case TIFFTAG_ORIENTATION:
		*va_arg(ap, uint16 *) = td->td_orientation;
		return (1);
	case TIFFTAG_SAMPLESPERPIXEL:
		*va_arg(ap, uint16 *) = td->td_samplesperpixel;
		return (1);
	case TIFFTAG_ROWSPERSTRIP:
		*va_arg(ap, uint32 *) = td->td_rowsperstrip;
		return (1);
	case TIFFTAG_MINSAMPLEVALUE:
		*va_arg(ap, uint16 *) = td->td_minsamplevalue;
		return (1);
	case TIFFTAG_MAXSAMPLEVALUE:
		*va_arg(ap, uint16 *) = td->td_maxsamplevalue;
		return (1);
	case TIFFTAG_PLANARCONFIG:
		*va_arg(ap, uint16 *) = td->td_planarconfig;
		return (1);
	case TIFFTAG_RESOLUTIONUNIT:
		*va_arg(ap, uint16 *) = td->td_resolutionunit;
		return (1);
#ifdef CMYK_SUPPORT
	case TIFFTAG_DOTRANGE:
		*va_arg(ap, uint16 *) = 0;
		*va_arg(ap, uint16 *) = (1<<td->td_bitspersample)-1;
		return (1);
	case TIFFTAG_INKSET:
		*va_arg(ap, uint16 *) = td->td_inkset;
		return (1);
	case TIFFTAG_NUMBEROFINKS:
		*va_arg(ap, uint16 *) = td->td_ninks;
		return (1);
#endif
	case TIFFTAG_EXTRASAMPLES:
		*va_arg(ap, uint16 *) = td->td_extrasamples;
		*va_arg(ap, uint16 **) = td->td_sampleinfo;
		return (1);
	case TIFFTAG_MATTEING:
		*va_arg(ap, uint16 *) =
		    (td->td_extrasamples == 1 &&
		     td->td_sampleinfo[0] == EXTRASAMPLE_ASSOCALPHA);
		return (1);
	case TIFFTAG_TILEDEPTH:
		*va_arg(ap, uint32 *) = td->td_tiledepth;
		return (1);
	case TIFFTAG_DATATYPE:
		*va_arg(ap, uint16 *) = td->td_sampleformat-1;
		return (1);
	case TIFFTAG_SAMPLEFORMAT:
		*va_arg(ap, uint16 *) = td->td_sampleformat;
                return(1);
	case TIFFTAG_IMAGEDEPTH:
		*va_arg(ap, uint32 *) = td->td_imagedepth;
		return (1);
#ifdef YCBCR_SUPPORT
	case TIFFTAG_YCBCRCOEFFICIENTS:
		if (!td->td_ycbcrcoeffs) {
			td->td_ycbcrcoeffs = (float *)
			    _TIFFmalloc(3*sizeof (float));
			/* defaults are from CCIR Recommendation 601-1 */
			td->td_ycbcrcoeffs[0] = 0.299f;
			td->td_ycbcrcoeffs[1] = 0.587f;
			td->td_ycbcrcoeffs[2] = 0.114f;
		}
		*va_arg(ap, float **) = td->td_ycbcrcoeffs;
		return (1);
	case TIFFTAG_YCBCRSUBSAMPLING:
		*va_arg(ap, uint16 *) = td->td_ycbcrsubsampling[0];
		*va_arg(ap, uint16 *) = td->td_ycbcrsubsampling[1];
		return (1);
	case TIFFTAG_YCBCRPOSITIONING:
		*va_arg(ap, uint16 *) = td->td_ycbcrpositioning;
		return (1);
#endif
#ifdef COLORIMETRY_SUPPORT
	case TIFFTAG_TRANSFERFUNCTION:
		if (!td->td_transferfunction[0])
			TIFFDefaultTransferFunction(td);
		*va_arg(ap, uint16 **) = td->td_transferfunction[0];
		if (td->td_samplesperpixel - td->td_extrasamples > 1) {
			*va_arg(ap, uint16 **) = td->td_transferfunction[1];
			*va_arg(ap, uint16 **) = td->td_transferfunction[2];
		}
		return (1);
	case TIFFTAG_REFERENCEBLACKWHITE:
		if (!td->td_refblackwhite)
			TIFFDefaultRefBlackWhite(td);
		*va_arg(ap, float **) = td->td_refblackwhite;
		return (1);
#endif
	}
	return (0);
}

/*
 * Like TIFFGetField, but return any default
 * value if the tag is not present in the directory.
 */
int
TIFFGetFieldDefaulted(TIFF* tif, ttag_t tag, ...)
{
	int ok;
	va_list ap;

	va_start(ap, tag);
	ok =  TIFFVGetFieldDefaulted(tif, tag, ap);
	va_end(ap);
	return (ok);
}