一幅MxN尺寸的图像的PSNR的计算公式如下所示：
其中xij 和yij 分别表示失真图像和原始图像对应像素点的灰度值；
i，j 分别代表图像的行和列；
L 是图像灰度值可到达的动态范围，8位的灰度图像的L=2^8-1=255。
如果已知SSD，MxN尺寸图像的PSNR公式如下所示。
MSE=SSD*1/(M*N)
PSNR=10*lg(255^2/MSE)
。
dp:17
dp:28
dp:32
dp:36
代码：
// PSNR_CAL.cpp : 定义控制台应用程序的入口点。 //PSNR (Peak Signal to Noise Ratio) //峰值信噪比PSNR衡量图像失真或是噪声水平的客观标准。2个图像之间PSNR值越大，则越相似。普遍基准为30dB，30dB以下的图像劣化较为明显。 #include "stdafx.h" #include <stdlib.h> #include <stdio.h> #include <time.h> #include <math.h> #define VIDEO_WIDTH 1280 #define VIDEO_HEIGHT 720 #define VIDEO_FRAME_NUM 10 //frame number //编码解码YUV #define DEC_YUV_PATH "E:\\yuv\\\\bs3.yuv" //原YUV #define REF_YUV_PATH "E:\\yuv\\BasketballDrive_1920x1080_25_250.yuv" #define REF_YUV_422 0 //1:reference yuv is 422 format, 0:reference yuv is 420 format #define VIDEO_SIZE_Y VIDEO_HEIGHT*VIDEO_WIDTH #define VIDEO_SIZE_UV (VIDEO_HEIGHT*VIDEO_WIDTH)>>1 #define VIDEO_SIZE_YUV (VIDEO_SIZE_Y + VIDEO_SIZE_UV) #define CONV422 0 #define CAL_PSNR 1 int main() { FILE *fp_dec; FILE *fp_ref; int i, j, k, comp; #if CAL_PSNR unsigned char line_dec[5000]; unsigned char line_ref[5000]; int idiff; unsigned long diff_sum; int width, height; double psnr_frame; double psnr_sum[VIDEO_FRAME_NUM][3]; double psnr_total[3]; fp_dec = fopen(DEC_YUV_PATH, "rb"); fp_ref = fopen(REF_YUV_PATH, "rb"); if (fp_dec == NULL) { printf("\n DEC YUV file not found\n"); return 0; } if (fp_ref == NULL) { printf("\n REF YUV file not found\n"); return 0; } for (i = 0; i < VIDEO_FRAME_NUM; i++) { //Y for (comp = 0; comp < 3; comp++) { diff_sum = 0; if(comp ==0) { width = VIDEO_WIDTH; height = VIDEO_HEIGHT; } else { width = VIDEO_WIDTH /2; height = VIDEO_HEIGHT /2; } for (j = 0; j < height; j++) { fread(line_dec, 1, width, fp_dec); fread(line_ref, 1, width, fp_ref); //fwrite(line_ref, 1, width, fp_ref_422); //if(comp != 0) //UV // fwrite(line_ref, 1, width, fp_ref_422); for (k = 0; k < width; k++) { idiff = (int)(line_dec[k] - line_ref[k]); diff_sum += idiff*idiff; //if (k == 0 && j == 5 ) // printf("stop at %d", k); } //if (comp != 0 && REF_YUV_422 == 1) // if 422 format, skip one chroma line // fread(line_dec, 1, width, fp_dec); } psnr_frame = (double)255 * 255 * width* height; psnr_sum[i][comp] = 10.0 * log10(psnr_frame / (double)diff_sum); } printf("frame %d, Y PSNR is %f, Cb PSNR is %f,Cr PSNR is %f \n", i, psnr_sum[i][0], psnr_sum[i][1], psnr_sum[i][2]); } psnr_total[0] = 0; psnr_total[1] = 0; psnr_total[2] = 0; for (i = 0; i<VIDEO_FRAME_NUM; i++) { psnr_total[0] += psnr_sum[i][0]; psnr_total[1] += psnr_sum[i][1]; psnr_total[2] += psnr_sum[i][2]; } psnr_total[0] = psnr_total[0] / (VIDEO_FRAME_NUM); psnr_total[1] = psnr_total[1] / (VIDEO_FRAME_NUM); psnr_total[2] = psnr_total[2] / (VIDEO_FRAME_NUM); printf("average PSNR of sequence is:\n Y PSNR is %f, U PSNR is %f,V PSNR is %f\n", psnr_total[0], psnr_total[1], psnr_total[2]); fclose(fp_dec); fclose(fp_ref); system("pause"); #endif #if CONV422 //convert ref 4:2:0 yuv to interleave 4:2:2 yuv unsigned char Y_plane[VIDEO_SIZE_YUV]; unsigned char U_plane[VIDEO_SIZE_Y / 4]; unsigned char V_plane[VIDEO_SIZE_Y / 4]; unsigned char YUV_plane[2 * VIDEO_SIZE_Y]; unsigned char *pt0; unsigned char *pt1; unsigned char *pt2; unsigned char *pt3; fp_ref = fopen(REF_YUV_PATH, "rb"); fp_ref_422 = fopen(REF_YUV422_ITLV_PATH, "wb"); if (fp_ref == NULL) { printf("\n REF YUV file not found\n"); return 0; } if (fp_ref_422 == NULL) { printf("\n REF 422 YUV file not found\n"); return 0; } for (i = 0; i < VIDEO_FRAME_NUM_CONV; i++) { fread(Y_plane, 1, VIDEO_SIZE_Y, fp_ref); fread(U_plane, 1, VIDEO_SIZE_Y / 4, fp_ref); fread(V_plane, 1, VIDEO_SIZE_Y / 4, fp_ref); pt0 = Y_plane; pt1 = U_plane; pt2 = V_plane; pt3 = YUV_plane; for (j = 0; j < VIDEO_HEIGHT / 2; j++) { for (k = 0; k < VIDEO_WIDTH / 2; k++) //the row size of YUV_plane is 2*VIDEO_WIDTH { *pt3++ = *pt0++; //Y0 *pt3++ = *pt1++; //U0 *pt3++ = *pt0++; //Y1 *pt3++ = *pt2++; //V0 } pt1 = pt1 - VIDEO_WIDTH / 2; pt2 = pt2 - VIDEO_WIDTH / 2; for (k = 0; k < VIDEO_WIDTH / 2; k++) //the row size of YUV_plane is 2*VIDEO_WIDTH { *pt3++ = *pt0++; //Y(WIDTH+0) *pt3++ = *pt1++; //U0 *pt3++ = *pt0++; //Y(WIDTH+1) *pt3++ = *pt2++; //V0 } } fwrite(YUV_plane, 1, 2* VIDEO_SIZE_Y, fp_ref_422); } #endif } 文章来源: 视频质量评价PSNR