sys/src/cmd/jpg/rgbycc.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <draw.h>
   4
   5 float c1 = 1.402;
   6 float c2 = 0.34414;
   7 float c3 = 0.71414;
   8 float c4 = 1.772;
   9
  10 int
  11 closest(int Y, int Cb, int Cr)
  12 {
  13         double r, g, b;
  14         double diff, min;
  15         int rgb, R, G, B, v, i;
  16         int y1, cb1, cr1;
  17
  18         Cb -= 128;
  19         Cr -= 128;
  20         r = Y+c1*Cr;
  21         g = Y-c2*Cb-c3*Cr;
  22         b = Y+c4*Cb;
  23
  24 //print("YCbCr: %d %d %d, RGB: %g %g %g\n", Y, Cb, Cr, r, g, b);
  25
  26         min = 1000000.;
  27         v = 1000;
  28         for(i=0; i<256; i++){
  29                 rgb =  cmap2rgb(i);
  30                 R = (rgb >> 16) & 0xFF;
  31                 G = (rgb >> 8) & 0xFF;
  32                 B = (rgb >> 0) & 0xFF;
  33                 diff = (R-r)*(R-r) + (G-g)*(G-g) + (B-b)*(B-b);
  34                 y1 = 0.5870*G + 0.114*B + 0.299*R;
  35                 cb1 = (B-y1)/1.772;
  36                 cr1 = (R-y1)/1.402;
  37                 if(diff < min){
  38 //                      if(Y==0 && y1!=0)
  39 //                              continue;
  40                         if(Y==256-16 && y1<256-16)
  41                                 continue;
  42 //                      if(Cb==0 && cb1!=0)
  43 //                              continue;
  44                         if(Cb==256-16 && cb1<256-16)
  45                                 continue;
  46 //                      if(Cr==0 && cr1!=0)
  47 //                              continue;
  48                         if(Cr==256-16 && cr1<256-16)
  49                                 continue;
  50 //print("%d %d %d\n", R, G, B);
  51                         min = diff;
  52                         v = i;
  53                 }
  54         }
  55         if(v > 255)
  56                 abort();
  57         return v;
  58 }
  59
  60 void
  61 main(int argc, char *argv[])
  62 {
  63         int i, rgb;
  64         int r, g, b;
  65         double Y, Cr, Cb;
  66         int y, cb, cr;
  67         uchar close[16*16*16];
  68
  69 //print("%d\n", closest(atoi(argv[1]), atoi(argv[2]), atoi(argv[3])));
  70 //exits("X");
  71
  72         /* ycbcrmap */
  73         print("uint ycbcrmap[256] = {\n");
  74         for(i=0; i<256; i++){
  75                 if(i%8 == 0)
  76                         print("\t");
  77                 rgb = cmap2rgb(i);
  78                 r = (rgb>>16) & 0xFF;
  79                 g = (rgb>>8) & 0xFF;
  80                 b = (rgb>>0) & 0xFF;
  81                 Y = 0.5870*g + 0.114*b + 0.299*r;
  82                 Cr = (r-Y)/1.402 + 128.;
  83                 Cb = (b-Y)/1.772 + 128.;
  84                 if(Y<0. || Y>=256. || Cr<0. || Cr>=256. || Cb<0. || Cb>=256.)
  85                         print("bad at %d: %d %d %d; %g %g %g\n", i, r, g, b, Y, Cb, Cr);
  86                 r = Y;
  87                 g = Cb;
  88                 b = Cr;
  89                 print("0x%.6ulX, ", (r<<16) | (g<<8) | b);
  90                 if(i%8 == 7)
  91                         print("\n");
  92         }
  93         print("};\n\n");
  94
  95         /* closestycbcr */
  96         print("uchar closestycbcr[16*16*16] = {\n");
  97         for(y=0; y<256; y+=16)
  98         for(cb=0; cb<256; cb+=16)
  99         for(cr=0; cr<256; cr+=16)
 100                 close[(cr/16)+16*((cb/16)+16*(y/16))] = closest(y, cb, cr);
 101 if(0){
 102         /*weird: set white for nearly white */
 103         for(cb=128-32; cb<=128+32; cb+=16)
 104         for(cr=128-32; cr<=128+32; cr+=16)
 105                 close[(cr/16)+16*((cb/16)+16*(255/16))] = 0;
 106         /*weird: set black for nearly black */
 107         for(cb=128-32; cb<=128+32; cb+=16)
 108         for(cr=128-32; cr<=128+32; cr+=16)
 109                 close[(cr/16)+16*((cb/16)+16*(0/16))] = 255;
 110 }
 111         for(i=0; i<16*16*16; i++){
 112                 if(i%16 == 0)
 113                         print("\t");
 114                 print("%d,", close[i]);
 115                 if(i%16 == 15)
 116                         print("\n");
 117         }
 118         print("};\n\n");
 119         exits(nil);
 120 }