全参考视频质量评价方法

常用的方法有两种

1.PSNR(Peak Signal to Noise Ratio)峰值信噪比:一种评价图像的客观标准。

2.SSIM(structural similarity index)，结构相似性，是一种衡量两幅图像相似度的指标。SSIM使用的两张图像中，一张为未经压缩的无失真图像，另一张为失真后的图像。

PSNR_ C语言实现：

void PSNR_compute()

{

int width = //宽;

int height = //高;

uint8_t* p = (uint8_t*)malloc(width*height*3/2);

if (p == NULL) {

return;

}

size_t toread = width*height*3/2;

if (fread(p,1,toread,reference_file) != toread) {

free(p);

return;

}

const uint8_t* yptr = //y分量;

const uint8_t* cbptr = //cb分量;

const uint8_t* crptr = //cr分量;

int stride = Y的stride.

int cstride = U或者V的Stride;

double img_mse_y = MSE( yptr, stride, p, width, width, height);

double img_mse_cb = MSE(cbptr, cstride, p+width*height, width/2, width/2,height/2);

double img_mse_cr = MSE(crptr, cstride, p+width*height*5/4, width/2, width/2,height/2);

mse_frames++;

mse_y += img_mse_y;

mse_cb += img_mse_cb;

mse_cr += img_mse_cr;

printf("%5d %6f %6f %6f %6f\n",

framecnt,

PSNR(img_mse_y), PSNR(img_mse_cb), PSNR(img_mse_cr),

ssimSum);

free(p);

}

double MSE(const uint8_t* img, int imgStride,

const uint8_t* ref, int refStride,

int width, int height)

{

double sum=0.0;

const uint8_t* iPtr = img;

const uint8_t* rPtr = ref;

for (int y=0;y

uint32_t lineSum=0;

for (int x=0;x

int diff = iPtr[x] - rPtr[x];

lineSum += diff*diff;

}

sum += ((double)lineSum)/width;

iPtr += imgStride;

rPtr += refStride;

}

return sum/height;

}

double PSNR(double mse)

{

if (mse==0) { return 99.99999; }

return 10*log10(255.0*255.0/mse);

}

void main () {

while () {

//计算所有。

PSNR_compute()

}

//最终结果

printf("#total %6f %6f %6f %6f\n",

PSNR(mse_y /mse_frames),

PSNR(mse_cb/mse_frames),

PSNR(mse_cr/mse_frames),

ssim_y/ssim_frames);

}