python计算psnr

import cv2
import numpy as np
import math

def psnr(target, ref):
    #将图像格式转为float64
    target_data = np.array(target, dtype=np.float64)
    ref_data = np.array(ref,dtype=np.float64)
    # 直接相减，求差值
    diff = ref_data - target_data
    # 按第三个通道顺序把三维矩阵拉平
    diff = diff.flatten('C')
    # 计算MSE值
    rmse = math.sqrt(np.mean(diff ** 2.))
    # 精度
    eps = np.finfo(np.float64).eps
    if(rmse == 0):
        rmse = eps
    return 20*math.log10(255.0/rmse)

IMG_1 = cv2.imread("yuer.jpg",0)
IMG_2 = cv2.imread("june.jpg",0)

IMG_1 = np.resize(IMG_1, (100,100))
IMG_2 = np.resize(IMG_2, (100,100))

print(psnr(IMG_1,IMG_2))