--- /dev/null
+/* $Id: tif_color.c,v 1.1 2005-06-17 13:54:52 vp153 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 );
+
+ /* Turn luminosity to colour value. */
+ i = TIFFmin(cielab->range,
+ (int)((Yr - cielab->display.d_Y0R) / cielab->rstep));
+ *r = RINT(cielab->Yr2r[i]);
+
+ i = TIFFmin(cielab->range,
+ (int)((Yg - cielab->display.d_Y0G) / cielab->gstep));
+ *g = RINT(cielab->Yg2g[i]);
+
+ i = TIFFmin(cielab->range,
+ (int)((Yb - cielab->display.d_Y0B) / cielab->bstep));
+ *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))
+
+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 = CLAMP(Y, 0, 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 CLAMP
+#undef Code2V
+#undef SHIFT
+#undef ONE_HALF
+#undef FIX
+
+/* vim: set ts=8 sts=8 sw=8 noet: */
projects / opencv / blobdiff