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  1. /*
  2.  * Copyright (c) 2003-2013 Loren Merritt
  3.  *
  4.  * This program is free software; you can redistribute it and/or modify
  5.  * it under the terms of the GNU General Public License as published by
  6.  * the Free Software Foundation; either version 2 of the License, or
  7.  * (at your option) any later version.
  8.  *
  9.  * This program is distributed in the hope that it will be useful,
  10.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12.  * GNU General Public License for more details.
  13.  *
  14.  * You should have received a copy of the GNU General Public License
  15.  * along with this program; if not, write to the Free Software
  16.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110 USA
  17.  */
  18. /*
  19.  * tiny_ssim.c
  20.  * Computes the Structural Similarity Metric between two rawYV12 video files.
  21.  * original algorithm:
  22.  * Z. Wang, A. C. Bovik, H. R. Sheikh and E. P. Simoncelli,
  23.  *   "Image quality assessment: From error visibility to structural similarity,"
  24.  *   IEEE Transactions on Image Processing, vol. 13, no. 4, pp. 600-612, Apr. 2004.
  25.  *
  26.  * To improve speed, this implementation uses the standard approximation of
  27.  * overlapped 8x8 block sums, rather than the original gaussian weights.
  28.  */
  29.  
  30. #include <inttypes.h>
  31. #include <math.h>
  32. #include <stdio.h>
  33. #include <stdlib.h>
  34.  
  35. #define FFSWAP(type,a,b) do{type SWAP_tmp= b; b= a; a= SWAP_tmp;}while(0)
  36. #define FFMIN(a,b) ((a) > (b) ? (b) : (a))
  37.  
  38. #define BIT_DEPTH 8
  39. #define PIXEL_MAX ((1 << BIT_DEPTH)-1)
  40. typedef uint8_t  pixel;
  41.  
  42. /****************************************************************************
  43.  * structural similarity metric
  44.  ****************************************************************************/
  45. static void ssim_4x4x2_core( const pixel *pix1, intptr_t stride1,
  46.                              const pixel *pix2, intptr_t stride2,
  47.                              int sums[2][4] )
  48. {
  49.     int x,y,z;
  50.  
  51.     for( z = 0; z < 2; z++ )
  52.     {
  53.         uint32_t s1 = 0, s2 = 0, ss = 0, s12 = 0;
  54.         for( y = 0; y < 4; y++ )
  55.             for( x = 0; x < 4; x++ )
  56.             {
  57.                 int a = pix1[x+y*stride1];
  58.                 int b = pix2[x+y*stride2];
  59.                 s1  += a;
  60.                 s2  += b;
  61.                 ss  += a*a;
  62.                 ss  += b*b;
  63.                 s12 += a*b;
  64.             }
  65.         sums[z][0] = s1;
  66.         sums[z][1] = s2;
  67.         sums[z][2] = ss;
  68.         sums[z][3] = s12;
  69.         pix1 += 4;
  70.         pix2 += 4;
  71.     }
  72. }
  73.  
  74. static float ssim_end1( int s1, int s2, int ss, int s12 )
  75. {
  76. /* Maximum value for 10-bit is: ss*64 = (2^10-1)^2*16*4*64 = 4286582784, which will overflow in some cases.
  77.  * s1*s1, s2*s2, and s1*s2 also obtain this value for edge cases: ((2^10-1)*16*4)^2 = 4286582784.
  78.  * Maximum value for 9-bit is: ss*64 = (2^9-1)^2*16*4*64 = 1069551616, which will not overflow. */
  79. #if BIT_DEPTH > 9
  80. #define type float
  81.     static const float ssim_c1 = .01*.01*PIXEL_MAX*PIXEL_MAX*64;
  82.     static const float ssim_c2 = .03*.03*PIXEL_MAX*PIXEL_MAX*64*63;
  83. #else
  84. #define type int
  85.     static const int ssim_c1 = (int)(.01*.01*PIXEL_MAX*PIXEL_MAX*64 + .5);
  86.     static const int ssim_c2 = (int)(.03*.03*PIXEL_MAX*PIXEL_MAX*64*63 + .5);
  87. #endif
  88.     type fs1 = s1;
  89.     type fs2 = s2;
  90.     type fss = ss;
  91.     type fs12 = s12;
  92.     type vars = fss*64 - fs1*fs1 - fs2*fs2;
  93.     type covar = fs12*64 - fs1*fs2;
  94.     return (float)(2*fs1*fs2 + ssim_c1) * (float)(2*covar + ssim_c2)
  95.          / ((float)(fs1*fs1 + fs2*fs2 + ssim_c1) * (float)(vars + ssim_c2));
  96. #undef type
  97. }
  98.  
  99. static float ssim_end4( int sum0[5][4], int sum1[5][4], int width )
  100. {
  101.     float ssim = 0.0;
  102.     int i;
  103.  
  104.     for( i = 0; i < width; i++ )
  105.         ssim += ssim_end1( sum0[i][0] + sum0[i+1][0] + sum1[i][0] + sum1[i+1][0],
  106.                            sum0[i][1] + sum0[i+1][1] + sum1[i][1] + sum1[i+1][1],
  107.                            sum0[i][2] + sum0[i+1][2] + sum1[i][2] + sum1[i+1][2],
  108.                            sum0[i][3] + sum0[i+1][3] + sum1[i][3] + sum1[i+1][3] );
  109.     return ssim;
  110. }
  111.  
  112. float ssim_plane(
  113.                            pixel *pix1, intptr_t stride1,
  114.                            pixel *pix2, intptr_t stride2,
  115.                            int width, int height, void *buf, int *cnt )
  116. {
  117.     int z = 0;
  118.     int x, y;
  119.     float ssim = 0.0;
  120.     int (*sum0)[4] = buf;
  121.     int (*sum1)[4] = sum0 + (width >> 2) + 3;
  122.     width >>= 2;
  123.     height >>= 2;
  124.     for( y = 1; y < height; y++ )
  125.     {
  126.         for( ; z <= y; z++ )
  127.         {
  128.             FFSWAP( void*, sum0, sum1 );
  129.             for( x = 0; x < width; x+=2 )
  130.                 ssim_4x4x2_core( &pix1[4*(x+z*stride1)], stride1, &pix2[4*(x+z*stride2)], stride2, &sum0[x] );
  131.         }
  132.         for( x = 0; x < width-1; x += 4 )
  133.             ssim += ssim_end4( sum0+x, sum1+x, FFMIN(4,width-x-1) );
  134.     }
  135. //     *cnt = (height-1) * (width-1);
  136.     return ssim / ((height-1) * (width-1));
  137. }
  138.  
  139.  
  140. uint64_t ssd_plane( const uint8_t *pix1, const uint8_t *pix2, int size )
  141. {
  142.     uint64_t ssd = 0;
  143.     int i;
  144.     for( i=0; i<size; i++ )
  145.     {
  146.         int d = pix1[i] - pix2[i];
  147.         ssd += d*d;
  148.     }
  149.     return ssd;
  150. }
  151.  
  152. double ssd_to_psnr( uint64_t ssd, uint64_t denom )
  153. {
  154.     return -10*log((double)ssd/(denom*255*255))/log(10);
  155. }
  156.  
  157. int main(int argc, char* argv[])
  158. {
  159.     FILE *f[2];
  160.     uint8_t *buf[2], *plane[2][3];
  161.     int *temp;
  162.     uint64_t ssd[3] = {0,0,0};
  163.     double ssim[3] = {0,0,0};
  164.     int frame_size, w, h;
  165.     int frames, seek;
  166.     int i;
  167.  
  168.     if( argc<4 || 2 != sscanf(argv[3], "%dx%d", &w, &h) )
  169.     {
  170.         printf("tiny_ssim <file1.yuv> <file2.yuv> <width>x<height> [<seek>]\n");
  171.         return -1;
  172.     }
  173.  
  174.     f[0] = fopen(argv[1], "rb");
  175.     f[1] = fopen(argv[2], "rb");
  176.     sscanf(argv[3], "%dx%d", &w, &h);
  177.     frame_size = w*h*3/2;
  178.     for( i=0; i<2; i++ )
  179.     {
  180.         buf[i] = malloc(frame_size);
  181.         plane[i][0] = buf[i];
  182.         plane[i][1] = plane[i][0] + w*h;
  183.         plane[i][2] = plane[i][1] + w*h/4;
  184.     }
  185.     temp = malloc((2*w+12)*sizeof(*temp));
  186.     seek = argc<5 ? 0 : atoi(argv[4]);
  187.     fseek(f[seek<0], seek < 0 ? -seek : seek, SEEK_SET);
  188.  
  189.     for( frames=0;; frames++ )
  190.     {
  191.         if( fread(buf[0], frame_size, 1, f[0]) != 1) break;
  192.         if( fread(buf[1], frame_size, 1, f[1]) != 1) break;
  193.         for( i=0; i<3; i++ )
  194.         {
  195.             ssd[i]  += ssd_plane ( plane[0][i], plane[1][i], w*h>>2*!!i );
  196.             ssim[i] += ssim_plane( plane[0][i], w>>!!i,
  197.                                    plane[1][i], w>>!!i,
  198.                                    w>>!!i, h>>!!i, temp, NULL );
  199.         }
  200.     }
  201.  
  202.     if( !frames ) return 0;
  203.  
  204.     printf( "PSNR Y:%.3f  U:%.3f  V:%.3f  All:%.3f\n",
  205.             ssd_to_psnr( ssd[0], (uint64_t)frames*w*h ),
  206.             ssd_to_psnr( ssd[1], (uint64_t)frames*w*h/4 ),
  207.             ssd_to_psnr( ssd[2], (uint64_t)frames*w*h/4 ),
  208.             ssd_to_psnr( ssd[0] + ssd[1] + ssd[2], (uint64_t)frames*w*h*3/2 ) );
  209.     printf( "SSIM Y:%.5f U:%.5f V:%.5f All:%.5f\n",
  210.             ssim[0] / frames,
  211.             ssim[1] / frames,
  212.             ssim[2] / frames,
  213.             (ssim[0]*4 + ssim[1] + ssim[2]) / (frames*6) );
  214.  
  215.     return 0;
  216. }
  217.