src/tiff/tif_color.c

   1 /* $Header$ */
   2
   3 /*
   4  * Copyright (c) 1988-1997 Sam Leffler
   5  * Copyright (c) 1991-1997 Silicon Graphics, Inc.
   6  *
   7  * Permission to use, copy, modify, distribute, and sell this software and
   8  * its documentation for any purpose is hereby granted without fee, provided
   9  * that (i) the above copyright notices and this permission notice appear in
  10  * all copies of the software and related documentation, and (ii) the names of
  11  * Sam Leffler and Silicon Graphics may not be used in any advertising or
  12  * publicity relating to the software without the specific, prior written
  13  * permission of Sam Leffler and Silicon Graphics.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
  17  * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
  18  *
  19  * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
  20  * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
  21  * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
  22  * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
  23  * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  24  * OF THIS SOFTWARE.
  25  */
  26
  27 /*
  28  * CIE L*a*b* to CIE XYZ and CIE XYZ to RGB conversion routines are taken
  29  * from the VIPS library (http://www.vips.ecs.soton.ac.uk) with
  30  * the permission of John Cupitt, the VIPS author.
  31  */
  32
  33 /*
  34  * TIFF Library.
  35  *
  36  * Color space conversion routines.
  37  */
  38
  39 #include "tiffiop.h"
  40 #include <math.h>
  41
  42 /*
  43  * Convert color value from the CIE L*a*b* 1976 space to CIE XYZ.
  44  */
  45 void
  46 TIFFCIELabToXYZ(TIFFCIELabToRGB *cielab, uint32 l, int32 a, int32 b,
  47                 float *X, float *Y, float *Z)
  48 {
  49         float L = (float)l * 100.0F / 255.0F;
  50         float cby, tmp;
  51
  52         if( L < 8.856F ) {
  53                 *Y = (L * cielab->Y0) / 903.292F;
  54                 cby = 7.787F * (*Y / cielab->Y0) + 16.0F / 116.0F;
  55         } else {
  56                 cby = (L + 16.0F) / 116.0F;
  57                 *Y = cielab->Y0 * cby * cby * cby;
  58         }
  59
  60         tmp = (float)a / 500.0F + cby;
  61         if( tmp < 0.2069F )
  62                 *X = cielab->X0 * (tmp - 0.13793F) / 7.787F;
  63         else
  64                 *X = cielab->X0 * tmp * tmp * tmp;
  65
  66         tmp = cby - (float)b / 200.0F;
  67         if( tmp < 0.2069F )
  68                 *Z = cielab->Z0 * (tmp - 0.13793F) / 7.787F;
  69         else
  70                 *Z = cielab->Z0 * tmp * tmp * tmp;
  71 }
  72
  73 #define RINT(R) ((uint32)((R)>0?((R)+0.5):((R)-0.5)))
  74 /*
  75  * Convert color value from the XYZ space to RGB.
  76  */
  77 void
  78 TIFFXYZToRGB(TIFFCIELabToRGB *cielab, float X, float Y, float Z,
  79              uint32 *r, uint32 *g, uint32 *b)
  80 {
  81         int i;
  82         float Yr, Yg, Yb;
  83         float *matrix = &cielab->display.d_mat[0][0];
  84
  85         /* Multiply through the matrix to get luminosity values. */
  86         Yr =  matrix[0] * X + matrix[1] * Y + matrix[2] * Z;
  87         Yg =  matrix[3] * X + matrix[4] * Y + matrix[5] * Z;
  88         Yb =  matrix[6] * X + matrix[7] * Y + matrix[8] * Z;
  89
  90         /* Clip input */
  91         Yr = TIFFmax( Yr, cielab->display.d_Y0R );
  92         Yg = TIFFmax( Yg, cielab->display.d_Y0G );
  93         Yb = TIFFmax( Yb, cielab->display.d_Y0B );
  94
  95         /* Turn luminosity to colour value. */
  96         i = TIFFmin(cielab->range,
  97                     (int)((Yr - cielab->display.d_Y0R) / cielab->rstep));
  98         *r = RINT(cielab->Yr2r[i]);
  99
 100         i = TIFFmin(cielab->range,
 101                     (int)((Yg - cielab->display.d_Y0G) / cielab->gstep));
 102         *g = RINT(cielab->Yg2g[i]);
 103
 104         i = TIFFmin(cielab->range,
 105                     (int)((Yb - cielab->display.d_Y0B) / cielab->bstep));
 106         *b = RINT(cielab->Yb2b[i]);
 107
 108         /* Clip output. */
 109         *r = TIFFmin( *r, cielab->display.d_Vrwr );
 110         *g = TIFFmin( *g, cielab->display.d_Vrwg );
 111         *b = TIFFmin( *b, cielab->display.d_Vrwb );
 112 }
 113 #undef RINT
 114
 115 /*
 116  * Allocate conversion state structures and make look_up tables for
 117  * the Yr,Yb,Yg <=> r,g,b conversions.
 118  */
 119 int
 120 TIFFCIELabToRGBInit(TIFFCIELabToRGB* cielab,
 121                     TIFFDisplay *display, float *refWhite)
 122 {
 123         int i;
 124         float gamma;
 125
 126         cielab->range = CIELABTORGB_TABLE_RANGE;
 127
 128         _TIFFmemcpy(&cielab->display, display, sizeof(TIFFDisplay));
 129
 130         /* Red */
 131         gamma = 1.0F / cielab->display.d_gammaR ;
 132         cielab->rstep =
 133                 (cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;
 134         for(i = 0; i <= cielab->range; i++) {
 135                 cielab->Yr2r[i] = cielab->display.d_Vrwr
 136                     * ((float)pow((double)i / cielab->range, gamma));
 137         }
 138
 139         /* Green */
 140         gamma = 1.0F / cielab->display.d_gammaG ;
 141         cielab->gstep =
 142             (cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;
 143         for(i = 0; i <= cielab->range; i++) {
 144                 cielab->Yg2g[i] = cielab->display.d_Vrwg
 145                     * ((float)pow((double)i / cielab->range, gamma));
 146         }
 147
 148         /* Blue */
 149         gamma = 1.0F / cielab->display.d_gammaB ;
 150         cielab->bstep =
 151             (cielab->display.d_YCR - cielab->display.d_Y0R) / cielab->range;
 152         for(i = 0; i <= cielab->range; i++) {
 153                 cielab->Yb2b[i] = cielab->display.d_Vrwb
 154                     * ((float)pow((double)i / cielab->range, gamma));
 155         }
 156
 157         /* Init reference white point */
 158         cielab->X0 = refWhite[0];
 159         cielab->Y0 = refWhite[1];
 160         cielab->Z0 = refWhite[2];
 161
 162         return 0;
 163 }
 164
 165 /*
 166  * Convert color value from the YCbCr space to CIE XYZ.
 167  * The colorspace conversion algorithm comes from the IJG v5a code;
 168  * see below for more information on how it works.
 169  */
 170 #define SHIFT                   16
 171 #define FIX(x)                  ((int32)((x) * (1L<<SHIFT) + 0.5))
 172 #define ONE_HALF                ((int32)(1<<(SHIFT-1)))
 173 #define Code2V(c, RB, RW, CR)   ((((c)-(int32)(RB))*(float)(CR))/(float)((RW)-(RB)))
 174 #define CLAMP(f,min,max)        ((f)<(min)?(min):(f)>(max)?(max):(f))
 175
 176 void
 177 TIFFYCbCrtoRGB(TIFFYCbCrToRGB *ycbcr, uint32 Y, int32 Cb, int32 Cr,
 178                uint32 *r, uint32 *g, uint32 *b)
 179 {
 180         /* XXX: Only 8-bit YCbCr input supported for now */
 181         Y = CLAMP(Y, 0, 255), Cb = CLAMP(Cb, 0, 255), Cr = CLAMP(Cr, 0, 255);
 182
 183         *r = ycbcr->clamptab[ycbcr->Y_tab[Y] + ycbcr->Cr_r_tab[Cr]];
 184         *g = ycbcr->clamptab[ycbcr->Y_tab[Y]
 185             + (int)((ycbcr->Cb_g_tab[Cb] + ycbcr->Cr_g_tab[Cr]) >> SHIFT)];
 186         *b = ycbcr->clamptab[ycbcr->Y_tab[Y] + ycbcr->Cb_b_tab[Cb]];
 187 }
 188
 189 /*
 190  * Initialize the YCbCr->RGB conversion tables.  The conversion
 191  * is done according to the 6.0 spec:
 192  *
 193  *    R = Y + Cr*(2 - 2*LumaRed)
 194  *    B = Y + Cb*(2 - 2*LumaBlue)
 195  *    G =   Y
 196  *        - LumaBlue*Cb*(2-2*LumaBlue)/LumaGreen
 197  *        - LumaRed*Cr*(2-2*LumaRed)/LumaGreen
 198  *
 199  * To avoid floating point arithmetic the fractional constants that
 200  * come out of the equations are represented as fixed point values
 201  * in the range 0...2^16.  We also eliminate multiplications by
 202  * pre-calculating possible values indexed by Cb and Cr (this code
 203  * assumes conversion is being done for 8-bit samples).
 204  */
 205 int
 206 TIFFYCbCrToRGBInit(TIFFYCbCrToRGB* ycbcr, float *luma, float *refBlackWhite)
 207 {
 208     TIFFRGBValue* clamptab;
 209     int i;
 210
 211 #define LumaRed     luma[0]
 212 #define LumaGreen   luma[1]
 213 #define LumaBlue    luma[2]
 214
 215     clamptab = (TIFFRGBValue*)(
 216         (tidata_t) ycbcr+TIFFroundup(sizeof (TIFFYCbCrToRGB), sizeof (long)));
 217     _TIFFmemset(clamptab, 0, 256);              /* v < 0 => 0 */
 218     ycbcr->clamptab = (clamptab += 256);
 219     for (i = 0; i < 256; i++)
 220         clamptab[i] = (TIFFRGBValue) i;
 221     _TIFFmemset(clamptab+256, 255, 2*256);      /* v > 255 => 255 */
 222     ycbcr->Cr_r_tab = (int*) (clamptab + 3*256);
 223     ycbcr->Cb_b_tab = ycbcr->Cr_r_tab + 256;
 224     ycbcr->Cr_g_tab = (int32*) (ycbcr->Cb_b_tab + 256);
 225     ycbcr->Cb_g_tab = ycbcr->Cr_g_tab + 256;
 226     ycbcr->Y_tab = ycbcr->Cb_g_tab + 256;
 227
 228     { float f1 = 2-2*LumaRed;           int32 D1 = FIX(f1);
 229       float f2 = LumaRed*f1/LumaGreen;  int32 D2 = -FIX(f2);
 230       float f3 = 2-2*LumaBlue;          int32 D3 = FIX(f3);
 231       float f4 = LumaBlue*f3/LumaGreen; int32 D4 = -FIX(f4);
 232       int x;
 233
 234 #undef LumaBlue
 235 #undef LumaGreen
 236 #undef LumaRed
 237
 238       /*
 239        * i is the actual input pixel value in the range 0..255
 240        * Cb and Cr values are in the range -128..127 (actually
 241        * they are in a range defined by the ReferenceBlackWhite
 242        * tag) so there is some range shifting to do here when
 243        * constructing tables indexed by the raw pixel data.
 244        */
 245       for (i = 0, x = -128; i < 256; i++, x++) {
 246             int32 Cr = (int32)Code2V(x, refBlackWhite[4] - 128.0F,
 247                             refBlackWhite[5] - 128.0F, 127);
 248             int32 Cb = (int32)Code2V(x, refBlackWhite[2] - 128.0F,
 249                             refBlackWhite[3] - 128.0F, 127);
 250
 251             ycbcr->Cr_r_tab[i] = (int32)((D1*Cr + ONE_HALF)>>SHIFT);
 252             ycbcr->Cb_b_tab[i] = (int32)((D3*Cb + ONE_HALF)>>SHIFT);
 253             ycbcr->Cr_g_tab[i] = D2*Cr;
 254             ycbcr->Cb_g_tab[i] = D4*Cb + ONE_HALF;
 255             ycbcr->Y_tab[i] =
 256                     (int32)Code2V(x + 128, refBlackWhite[0], refBlackWhite[1], 255);
 257       }
 258     }
 259
 260     return 0;
 261 }
 262 #undef  CLAMP
 263 #undef  Code2V
 264 #undef  SHIFT
 265 #undef  ONE_HALF
 266 #undef  FIX
 267
 268