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/* $Id: tif_color.c,v 1.2 2009/08/21 04:01:59 scuri Exp $ */
/*
* Copyright (c) 1988-1997 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.
*/
/*
* CIE L*a*b* to CIE XYZ and CIE XYZ to RGB conversion routines are taken
* from the VIPS library (http://www.vips.ecs.soton.ac.uk) with
* the permission of John Cupitt, the VIPS author.
*/
/*
* TIFF Library.
*
* Color space conversion routines.
*/
#include "tiffiop.h"
#include <math.h>
/*
* Convert color value from the CIE L*a*b* 1976 space to CIE XYZ.
*/
void
TIFFCIELabToXYZ(TIFFCIELabToRGB *cielab, uint32 l, int32 a, int32 b,
float *X, float *Y, float *Z)
{
float L = (float)l * 100.0F / 255.0F;
float cby, tmp;
if( L < 8.856F ) {
*Y = (L * cielab->Y0) / 903.292F;
cby = 7.787F * (*Y / cielab->Y0) + 16.0F / 116.0F;
} else {
cby = (L + 16.0F) / 116.0F;
*Y = cielab->Y0 * cby * cby * cby;
}
tmp = (float)a / 500.0F + cby;
if( tmp < 0.2069F )
*X = cielab->X0 * (tmp - 0.13793F) / 7.787F;
else
*X = cielab->X0 * tmp * tmp * tmp;
tmp = cby - (float)b / 200.0F;
if( tmp < 0.2069F )
*Z = cielab->Z0 * (tmp - 0.13793F) / 7.787F;
else
*Z = cielab->Z0 * tmp * tmp * tmp;
}
#define RINT(R) ((uint32)((R)>0?((R)+0.5):((R)-0.5)))
/*
* Convert color value from the XYZ space to RGB.
*/
void
TIFFXYZToRGB(TIFFCIELabToRGB *cielab, float X, float Y, float Z,
uint32 *r, uint32 *g, uint32 *b)
{
int i;
float Yr, Yg, Yb;
float *matrix = &cielab->display.d_mat[0][0];
/* Multiply through the matrix to get luminosity values. */
Yr = matrix[0] * X + matrix[1] * Y + matrix[2] * Z;
Yg = matrix[3] * X + matrix[4] * Y + matrix[5] * Z;
Yb = matrix[6] * X + matrix[7] * Y + matrix[8] * Z;
/* Clip input */
Yr = TIFFmax(Yr, cielab->display.d_Y0R);
Yg = TIFFmax(Yg, cielab->display.d_Y0G);
Yb = TIFFmax(Yb, cielab->display.d_Y0B);
/* Avoid overflow in case of wrong input values */
Yr = TIFFmin(Yr, cielab->display.d_YCR);
Yg = TIFFmin(Yg, cielab->display.d_YCG);
Yb = TIFFmin(Yb, cielab->display.d_YCB);
/* Turn luminosity to colour value. */
i = (int)((Yr - cielab->display.d_Y0R) / cielab->rstep);
i = TIFFmin(cielab->range, i);
*r = RINT(cielab->Yr2r[i]);
i = (int)((Yg - cielab->display.d_Y0G) / cielab->gstep);
i = TIFFmin(cielab->range, i);
*g = RINT(cielab->Yg2g[i]);
i = (int)((Yb - cielab->display.d_Y0B) / cielab->bstep);
i = TIFFmin(cielab->range, i);
*b = RINT(cielab->Yb2b[i]);
/* Clip output. */
*r = TIFFmin(*r, cielab->display.d_Vrwr);
*g = TIFFmin(*g, cielab->display.d_Vrwg);
*b = TIFFmin(*b, cielab->display.d_Vrwb);
}
#undef RINT
/*
* Allocate conversion state structures and make look_up tables for
* the Yr,Yb,Yg <=> r,g,b conversions.
*/
int
TIFFCIELabToRGBInit(TIFFCIELabToRGB* cielab,
TIFFDisplay *display, float *refWhite)
{
int i;
double gamma;
cielab->range = CIELABTORGB_TABLE_RANGE;
_TIFFmemcpy(&cielab->display, display, sizeof(TIFFDisplay));
/* Red */
gamma = 1.0 / cielab->display.d_gammaR ;
cielab->rstep =
(cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;
for(i = 0; i <= cielab->range; i++) {
cielab->Yr2r[i] = cielab->display.d_Vrwr
* ((float)pow((double)i / cielab->range, gamma));
}
/* Green */
gamma = 1.0 / cielab->display.d_gammaG ;
cielab->gstep =
(cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;
for(i = 0; i <= cielab->range; i++) {
cielab->Yg2g[i] = cielab->display.d_Vrwg
* ((float)pow((double)i / cielab->range, gamma));
}
/* Blue */
gamma = 1.0 / cielab->display.d_gammaB ;
cielab->bstep =
(cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;
for(i = 0; i <= cielab->range; i++) {
cielab->Yb2b[i] = cielab->display.d_Vrwb
* ((float)pow((double)i / cielab->range, gamma));
}
/* Init reference white point */
cielab->X0 = refWhite[0];
cielab->Y0 = refWhite[1];
cielab->Z0 = refWhite[2];
return 0;
}
/*
* Convert color value from the YCbCr space to CIE XYZ.
* The colorspace conversion algorithm comes from the IJG v5a code;
* see below for more information on how it works.
*/
#define SHIFT 16
#define FIX(x) ((int32)((x) * (1L<<SHIFT) + 0.5))
#define ONE_HALF ((int32)(1<<(SHIFT-1)))
#define Code2V(c, RB, RW, CR) ((((c)-(int32)(RB))*(float)(CR))/(float)(((RW)-(RB)) ? ((RW)-(RB)) : 1))
#define CLAMP(f,min,max) ((f)<(min)?(min):(f)>(max)?(max):(f))
#define HICLAMP(f,max) ((f)>(max)?(max):(f))
void
TIFFYCbCrtoRGB(TIFFYCbCrToRGB *ycbcr, uint32 Y, int32 Cb, int32 Cr,
uint32 *r, uint32 *g, uint32 *b)
{
/* XXX: Only 8-bit YCbCr input supported for now */
Y = HICLAMP(Y, 255), Cb = CLAMP(Cb, 0, 255), Cr = CLAMP(Cr, 0, 255);
*r = ycbcr->clamptab[ycbcr->Y_tab[Y] + ycbcr->Cr_r_tab[Cr]];
*g = ycbcr->clamptab[ycbcr->Y_tab[Y]
+ (int)((ycbcr->Cb_g_tab[Cb] + ycbcr->Cr_g_tab[Cr]) >> SHIFT)];
*b = ycbcr->clamptab[ycbcr->Y_tab[Y] + ycbcr->Cb_b_tab[Cb]];
}
/*
* 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).
*/
int
TIFFYCbCrToRGBInit(TIFFYCbCrToRGB* ycbcr, float *luma, float *refBlackWhite)
{
TIFFRGBValue* clamptab;
int i;
#define LumaRed luma[0]
#define LumaGreen luma[1]
#define LumaBlue luma[2]
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] = (TIFFRGBValue) i;
_TIFFmemset(clamptab+256, 255, 2*256); /* v > 255 => 255 */
ycbcr->Cr_r_tab = (int*) (clamptab + 3*256);
ycbcr->Cb_b_tab = ycbcr->Cr_r_tab + 256;
ycbcr->Cr_g_tab = (int32*) (ycbcr->Cb_b_tab + 256);
ycbcr->Cb_g_tab = ycbcr->Cr_g_tab + 256;
ycbcr->Y_tab = ycbcr->Cb_g_tab + 256;
{ float f1 = 2-2*LumaRed; int32 D1 = FIX(f1);
float f2 = LumaRed*f1/LumaGreen; int32 D2 = -FIX(f2);
float f3 = 2-2*LumaBlue; int32 D3 = FIX(f3);
float f4 = LumaBlue*f3/LumaGreen; int32 D4 = -FIX(f4);
int x;
#undef LumaBlue
#undef LumaGreen
#undef LumaRed
/*
* i is the actual input pixel value in the range 0..255
* Cb and Cr values are in the range -128..127 (actually
* they are in a range defined by the ReferenceBlackWhite
* tag) so there is some range shifting to do here when
* constructing tables indexed by the raw pixel data.
*/
for (i = 0, x = -128; i < 256; i++, x++) {
int32 Cr = (int32)Code2V(x, refBlackWhite[4] - 128.0F,
refBlackWhite[5] - 128.0F, 127);
int32 Cb = (int32)Code2V(x, refBlackWhite[2] - 128.0F,
refBlackWhite[3] - 128.0F, 127);
ycbcr->Cr_r_tab[i] = (int32)((D1*Cr + ONE_HALF)>>SHIFT);
ycbcr->Cb_b_tab[i] = (int32)((D3*Cb + ONE_HALF)>>SHIFT);
ycbcr->Cr_g_tab[i] = D2*Cr;
ycbcr->Cb_g_tab[i] = D4*Cb + ONE_HALF;
ycbcr->Y_tab[i] =
(int32)Code2V(x + 128, refBlackWhite[0], refBlackWhite[1], 255);
}
}
return 0;
}
#undef HICLAMP
#undef CLAMP
#undef Code2V
#undef SHIFT
#undef ONE_HALF
#undef FIX
/* vim: set ts=8 sts=8 sw=8 noet: */
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