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/*
* Copyright (c) 2003-2013 Loren Merritt
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110 USA
*/
/*
* tiny_ssim.c
* Computes the Structural Similarity Metric between two rawYV12 video files.
* original algorithm:
* Z. Wang, A. C. Bovik, H. R. Sheikh and E. P. Simoncelli,
* "Image quality assessment: From error visibility to structural similarity,"
* IEEE Transactions on Image Processing, vol. 13, no. 4, pp. 600-612, Apr. 2004.
*
* To improve speed, this implementation uses the standard approximation of
* overlapped 8x8 block sums, rather than the original gaussian weights.
*/
#include <inttypes.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#define FFSWAP(type,a,b) do{type SWAP_tmp= b; b= a; a= SWAP_tmp;}while(0)
#define FFMIN(a,b) ((a) > (b) ? (b) : (a))
#define BIT_DEPTH 8
#define PIXEL_MAX ((1 << BIT_DEPTH)-1)
typedef uint8_t pixel;
/****************************************************************************
* structural similarity metric
****************************************************************************/
static void ssim_4x4x2_core( const pixel *pix1, intptr_t stride1,
const pixel *pix2, intptr_t stride2,
int sums[2][4] )
{
int x,y,z;
for( z = 0; z < 2; z++ )
{
uint32_t s1 = 0, s2 = 0, ss = 0, s12 = 0;
for( y = 0; y < 4; y++ )
for( x = 0; x < 4; x++ )
{
int a = pix1[x+y*stride1];
int b = pix2[x+y*stride2];
s1 += a;
s2 += b;
ss += a*a;
ss += b*b;
s12 += a*b;
}
sums[z][0] = s1;
sums[z][1] = s2;
sums[z][2] = ss;
sums[z][3] = s12;
pix1 += 4;
pix2 += 4;
}
}
static float ssim_end1( int s1, int s2, int ss, int s12 )
{
/* Maximum value for 10-bit is: ss*64 = (2^10-1)^2*16*4*64 = 4286582784, which will overflow in some cases.
* s1*s1, s2*s2, and s1*s2 also obtain this value for edge cases: ((2^10-1)*16*4)^2 = 4286582784.
* Maximum value for 9-bit is: ss*64 = (2^9-1)^2*16*4*64 = 1069551616, which will not overflow. */
#if BIT_DEPTH > 9
#define type float
static const float ssim_c1 = .01*.01*PIXEL_MAX*PIXEL_MAX*64;
static const float ssim_c2 = .03*.03*PIXEL_MAX*PIXEL_MAX*64*63;
#else
#define type int
static const int ssim_c1 = (int)(.01*.01*PIXEL_MAX*PIXEL_MAX*64 + .5);
static const int ssim_c2 = (int)(.03*.03*PIXEL_MAX*PIXEL_MAX*64*63 + .5);
#endif
type fs1 = s1;
type fs2 = s2;
type fss = ss;
type fs12 = s12;
type vars = fss*64 - fs1*fs1 - fs2*fs2;
type covar = fs12*64 - fs1*fs2;
return (float)(2*fs1*fs2 + ssim_c1) * (float)(2*covar + ssim_c2)
/ ((float)(fs1*fs1 + fs2*fs2 + ssim_c1) * (float)(vars + ssim_c2));
#undef type
}
static float ssim_end4( int sum0[5][4], int sum1[5][4], int width )
{
float ssim = 0.0;
int i;
for( i = 0; i < width; i++ )
ssim += ssim_end1( sum0[i][0] + sum0[i+1][0] + sum1[i][0] + sum1[i+1][0],
sum0[i][1] + sum0[i+1][1] + sum1[i][1] + sum1[i+1][1],
sum0[i][2] + sum0[i+1][2] + sum1[i][2] + sum1[i+1][2],
sum0[i][3] + sum0[i+1][3] + sum1[i][3] + sum1[i+1][3] );
return ssim;
}
float ssim_plane(
pixel *pix1, intptr_t stride1,
pixel *pix2, intptr_t stride2,
int width, int height, void *buf, int *cnt )
{
int z = 0;
int x, y;
float ssim = 0.0;
int (*sum0)[4] = buf;
int (*sum1)[4] = sum0 + (width >> 2) + 3;
width >>= 2;
height >>= 2;
for( y = 1; y < height; y++ )
{
for( ; z <= y; z++ )
{
FFSWAP( void*, sum0, sum1 );
for( x = 0; x < width; x+=2 )
ssim_4x4x2_core( &pix1[4*(x+z*stride1)], stride1, &pix2[4*(x+z*stride2)], stride2, &sum0[x] );
}
for( x = 0; x < width-1; x += 4 )
ssim += ssim_end4( sum0+x, sum1+x, FFMIN(4,width-x-1) );
}
// *cnt = (height-1) * (width-1);
return ssim / ((height-1) * (width-1));
}
uint64_t ssd_plane( const uint8_t *pix1, const uint8_t *pix2, int size )
{
uint64_t ssd = 0;
int i;
for( i=0; i<size; i++ )
{
int d = pix1[i] - pix2[i];
ssd += d*d;
}
return ssd;
}
double ssd_to_psnr( uint64_t ssd, uint64_t denom )
{
return -10*log((double)ssd/(denom*255*255))/log(10);
}
int main(int argc, char* argv[])
{
FILE *f[2];
uint8_t *buf[2], *plane[2][3];
int *temp;
uint64_t ssd[3] = {0,0,0};
double ssim[3] = {0,0,0};
int frame_size, w, h;
int frames, seek;
int i;
if( argc<4 || 2 != sscanf(argv[3], "%dx%d", &w, &h) )
{
printf("tiny_ssim <file1.yuv> <file2.yuv> <width>x<height> [<seek>]\n");
return -1;
}
f[0] = fopen(argv[1], "rb");
f[1] = fopen(argv[2], "rb");
sscanf(argv[3], "%dx%d", &w, &h);
frame_size = w*h*3/2;
for( i=0; i<2; i++ )
{
buf[i] = malloc(frame_size);
plane[i][0] = buf[i];
plane[i][1] = plane[i][0] + w*h;
plane[i][2] = plane[i][1] + w*h/4;
}
temp = malloc((2*w+12)*sizeof(*temp));
seek = argc<5 ? 0 : atoi(argv[4]);
fseek(f[seek<0], seek < 0 ? -seek : seek, SEEK_SET);
for( frames=0;; frames++ )
{
if( fread(buf[0], frame_size, 1, f[0]) != 1) break;
if( fread(buf[1], frame_size, 1, f[1]) != 1) break;
for( i=0; i<3; i++ )
{
ssd[i] += ssd_plane ( plane[0][i], plane[1][i], w*h>>2*!!i );
ssim[i] += ssim_plane( plane[0][i], w>>!!i,
plane[1][i], w>>!!i,
w>>!!i, h>>!!i, temp, NULL );
}
}
if( !frames ) return 0;
printf( "PSNR Y:%.3f U:%.3f V:%.3f All:%.3f\n",
ssd_to_psnr( ssd[0], (uint64_t)frames*w*h ),
ssd_to_psnr( ssd[1], (uint64_t)frames*w*h/4 ),
ssd_to_psnr( ssd[2], (uint64_t)frames*w*h/4 ),
ssd_to_psnr( ssd[0] + ssd[1] + ssd[2], (uint64_t)frames*w*h*3/2 ) );
printf( "SSIM Y:%.5f U:%.5f V:%.5f All:%.5f\n",
ssim[0] / frames,
ssim[1] / frames,
ssim[2] / frames,
(ssim[0]*4 + ssim[1] + ssim[2]) / (frames*6) );
return 0;
}
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