sys/src/cmd/jpg/totruecolor.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <bio.h>
   4 #include <draw.h>
   5 #include "imagefile.h"
   6
   7 enum {
   8         c1 = 2871,      /* 1.402 * 2048 */
   9         c2 = 705,               /* 0.34414 * 2048 */
  10         c3 = 1463,      /* 0.71414 * 2048 */
  11         c4 = 3629,      /* 1.772 * 2048 */
  12 };
  13
  14 Rawimage*
  15 totruecolor(Rawimage *i, int chandesc)
  16 {
  17         int j, k;
  18         Rawimage *im;
  19         char err[ERRMAX];
  20         uchar *rp, *gp, *bp, *cmap, *inp, *outp, cmap1[3*256];
  21         int r, g, b, Y, Cr, Cb;
  22
  23         if(chandesc!=CY && chandesc!=CRGB24)
  24                 return _remaperror("remap: can't convert to chandesc %d", chandesc);
  25
  26         err[0] = '\0';
  27         errstr(err, sizeof err);        /* throw it away */
  28         im = malloc(sizeof(Rawimage));
  29         if(im == nil)
  30                 return nil;
  31         memset(im, 0, sizeof(Rawimage));
  32         if(chandesc == CY)
  33                 im->chanlen = i->chanlen;
  34         else
  35                 im->chanlen = 3*i->chanlen;
  36         im->chandesc = chandesc;
  37         im->chans[0] = malloc(im->chanlen);
  38         if(im->chans[0] == nil){
  39                 free(im);
  40                 return nil;
  41         }
  42         im->r = i->r;
  43         im->nchans = 1;
  44
  45         cmap = i->cmap;
  46
  47         outp = im->chans[0];
  48
  49         switch(i->chandesc){
  50         default:
  51                 return _remaperror("remap: can't recognize channel type %d", i->chandesc);
  52         case CY:
  53                 if(i->nchans != 1)
  54                         return _remaperror("remap: Y image has %d chans", i->nchans);
  55                 if(chandesc == CY){
  56                         memmove(im->chans[0], i->chans[0], i->chanlen);
  57                         break;
  58                 }
  59                 /* convert to three color */
  60                 inp = i->chans[0];
  61                 for(j=0; j<i->chanlen; j++){
  62                         k = *inp++;
  63                         *outp++ = k;
  64                         *outp++ = k;
  65                         *outp++ = k;
  66                 }
  67                 break;
  68
  69         case CRGB1:
  70                 if(cmap == nil)
  71                         return _remaperror("remap: image has no color map");
  72                 if(i->nchans != 1)
  73                         return _remaperror("remap: can't handle nchans %d", i->nchans);
  74                 for(j=1; j<=8; j++)
  75                         if(i->cmaplen == 3*(1<<j))
  76                                 break;
  77                 if(j > 8)
  78                         return _remaperror("remap: can't do colormap size 3*%d", i->cmaplen/3);
  79                 if(i->cmaplen != 3*256){
  80                         /* to avoid a range check in loop below, make a full-size cmap */
  81                         memmove(cmap1, cmap, i->cmaplen);
  82                         cmap = cmap1;
  83                 }
  84                 inp = i->chans[0];
  85                 if(chandesc == CY){
  86                         for(j=0; j<i->chanlen; j++){
  87                                 k = *inp++;
  88                                 r = cmap[3*k+2];
  89                                 g = cmap[3*k+1];
  90                                 b = cmap[3*k+0];
  91                                 r = (2125*r + 7154*g + 721*b)/10000;    /* Poynton page 84 */
  92                                 *outp++ = r;
  93                         }
  94                 }else{
  95                         for(j=0; j<i->chanlen; j++){
  96                                 k = *inp++;
  97                                 *outp++ = cmap[3*k+2];
  98                                 *outp++ = cmap[3*k+1];
  99                                 *outp++ = cmap[3*k+0];
 100                         }
 101                 }
 102                 break;
 103
 104         case CRGB:
 105                 if(i->nchans != 3)
 106                         return _remaperror("remap: can't handle nchans %d", i->nchans);
 107                 rp = i->chans[0];
 108                 gp = i->chans[1];
 109                 bp = i->chans[2];
 110                 if(chandesc == CY){
 111                         for(j=0; j<i->chanlen; j++){
 112                                 r = *bp++;
 113                                 g = *gp++;
 114                                 b = *rp++;
 115                                 r = (2125*r + 7154*g + 721*b)/10000;    /* Poynton page 84 */
 116                                 *outp++ = r;
 117                         }
 118                 }else
 119                         for(j=0; j<i->chanlen; j++){
 120                                 *outp++ = *bp++;
 121                                 *outp++ = *gp++;
 122                                 *outp++ = *rp++;
 123                         }
 124                 break;
 125
 126         case CYCbCr:
 127                 if(i->nchans != 3)
 128                         return _remaperror("remap: can't handle nchans %d", i->nchans);
 129                 rp = i->chans[0];
 130                 gp = i->chans[1];
 131                 bp = i->chans[2];
 132                 for(j=0; j<i->chanlen; j++){
 133                         Y = *rp++ << 11;
 134                         Cb = *gp++ - 128;
 135                         Cr = *bp++ - 128;
 136                         r = (Y+c1*Cr) >> 11;
 137                         g = (Y-c2*Cb-c3*Cr) >> 11;
 138                         b = (Y+c4*Cb) >> 11;
 139                         if(r < 0)
 140                                 r = 0;
 141                         if(r > 255)
 142                                 r = 255;
 143                         if(g < 0)
 144                                 g = 0;
 145                         if(g > 255)
 146                                 g = 255;
 147                         if(b < 0)
 148                                 b = 0;
 149                         if(b > 255)
 150                                 b = 255;
 151                         if(chandesc == CY){
 152                                 r = (2125*r + 7154*g + 721*b)/10000;
 153                                 *outp++ = r;
 154                         }else{
 155                                 *outp++ = b;
 156                                 *outp++ = g;
 157                                 *outp++ = r;
 158                         }
 159                 }
 160                 break;
 161         }
 162         return im;
 163 }