yuv2ppm.c

onmivision 摄相头模块驱动程序,blackfin 平台参考设计.

#include <stdio.h>
#include <stdlib.h>

/*
  yuv2ppm

  Converts Quantel YUV (UYUV) 4:2:2 images from ZapIt! to ppm.

  Written by Scott Scriven <[e-mail]>

  Released as public domain.
*/

/*
  Compile thusly:

  cc -o yuv2ppm yuv2ppm.c
*/

/* example.ppm  (ascii)
P3
# feep.ppm
4 4
15
 0  0  0    0  0  0    0  0  0   15  0 15
 0  0  0    0 15  7    0  0  0    0  0  0
 0  0  0    0  0  0    0 15  7    0  0  0
15  0 15    0  0  0    0  0  0    0  0  0
*/
/*
  Use "P6" for binary data, or "P3" for ascii data.
 */

int make_outfile(char *outfile, char *infile)
{
   int i;
   
   for(i=0; infile[i]; i++)
      outfile[i] = infile[i];

   outfile[i++] = '.';
   outfile[i++] = 'p';
   outfile[i++] = 'p';
   outfile[i++] = 'm';
   outfile[i++] = 0;
   
   return 0;
}


int yuv2rgb(int y, int u, int v)
{
   unsigned int pixel32;
   unsigned char *pixel = (unsigned char *)&pixel32;
   int r, g, b;
   
#if 0
   /*
     One formula I found:  (not the right one)
    
     R = 1.164(Y - 16) + 1.596(Cr - 128)
     G = 1.164(Y - 16) - 0.813(Cr - 128) - 0.391(Cb - 128)
     B = 1.164(Y - 16)                   + 2.018(Cb - 128)
   */
      
   r = (1.164 * (y - 16))
      + (2.018 * (v - 128));
   g = (1.164 * (y - 16))
      - (0.813 * (u - 128))
      - (0.391 * (v - 128));
   b = (1.164 * (y - 16))
      + (1.596 * (u - 128));
#else
   /*
     Another formula I found:  (seems to work)
     
     R = Y + 1.370705 (V-128)
     G = Y - 0.698001 (V-128) - 0.337633 (U-128)
     B = Y + 1.732446 (U-128)
   */
   
   r = y + (1.370705 * (v-128));
   g = y - (0.698001 * (v-128)) - (0.337633 * (u-128));
   b = y + (1.732446 * (u-128));
#endif

   // Even with proper conversion, some values still need clipping.
   if (r > 255) r = 255;
   if (g > 255) g = 255;
   if (b > 255) b = 255;
   if (r < 0) r = 0;
   if (g < 0) g = 0;
   if (b < 0) b = 0;

   // Values only go from 0-220..  Why?
   pixel[0] = r * 220 / 256;
   pixel[1] = g * 220 / 256;
   pixel[2] = b * 220 / 256;
   pixel[3] = 0;

   
   printf("yuv2rgb(%i, %i, %i) -> %i, %i, %i  (0x%x)\n",
	  y, u, v,
	  pixel[0], pixel[1], pixel[2],
	  pixel32);
  
   
   return pixel32;
}

int yuv2ppm(char *infile, char *outfile)
{
   FILE *in, *out;
   int i;
   unsigned int pixel_16;
   unsigned char pixel_24[3];
   unsigned int pixel32;
   int y, u, v, y2;
   
   char *ppmheader = "P6\n# Generated by yuv2ppm\n720 486\n255\n";

   in = fopen(infile, "rb");
   out = fopen(outfile, "wb");

   if (!in  ||  !out)  return 0;

   fprintf(out, ppmheader);

   for(i=0; i<352*288/2; i++)
   {
      fread(&pixel_16, 4, 1, in);

      pixel_24[0] = pixel_24[1] = pixel_24[2] = 0;
      
      u  = ((pixel_16 & 0x000000ff));
      y  = ((pixel_16 & 0x0000ff00)>>8);
      v  = ((pixel_16 & 0x00ff0000)>>16);
      y2 = ((pixel_16 & 0xff000000)>>24);


      pixel32 = yuv2rgb(y, u, v);
      pixel_24[0] = (pixel32 & 0x000000ff);
      pixel_24[1] = (pixel32 & 0x0000ff00) >> 8;
      pixel_24[2] = (pixel32 & 0x00ff0000) >> 16;
      
      // For binary PPM
      fwrite(pixel_24, 3, 1, out);
      // For ascii PPM
      //fprintf(out, "%i %i %i\n",
      //	 pixel_24[0],
      //	 pixel_24[1],
      //	 pixel_24[2]);
      
      pixel32 = yuv2rgb(y2, u, v);
      pixel_24[0] = (pixel32 & 0x000000ff);
      pixel_24[1] = (pixel32 & 0x0000ff00) >> 8;
      pixel_24[2] = (pixel32 & 0x00ff0000) >> 16;

      // For binary PPM
      fwrite(pixel_24, 3, 1, out);
      // For ascii PPM
      //fprintf(out, "%i %i %i\n",
      //	 pixel_24[0],
      //	 pixel_24[1],
      //	 pixel_24[2]);
	 

   }

   fclose(in);
   fclose(out);

   return 1;
}

int main(int argc, char **argv)
{
  char *infile, outfile[256];
  int i;
  int success;
  
  for(i=1; i<argc; i++)
  {
     success = 0;
     infile = argv[i];
     make_outfile(outfile, infile);
     
     printf("%s -> %s...  ", infile, outfile);
     fflush(stdout);

     success = yuv2ppm(infile, outfile);
     
     if(success)
     {
	printf("Done.\n");
     }
     else
     {
	printf("Failed.  Aborting.\n");
	return 1;
     }
  }

  return 0;
}