python 计算heic jpg PSNR

psnr峰值信噪比，
计算公式：

相同文件大小的jpg和heic的psnr

import cv2 as cv 
import math
import numpy as np
import pyheif
from PIL import Image
 
def psnr1(img1,img2):
    img1 =np.float64(img1)
    img2 =np.float64(img2)
    #compute mse
    # mse = np.mean((img1-img2)**2)
    mse = np.mean((img2/1.0-img1/1.0)**2)
    #compute psnr
    if mse < 1e-10:
        return 100
    psnr1 = 20*math.log10(255/math.sqrt(mse))
    return psnr1
 
def psnr2(img1,img2):
    img1 =np.float64(img1)
    img2 =np.float64(img2)
    mse = np.mean((img2/255.0-img1/255.0)**2)
    if mse < 1e-10:
        return 100
    psnr2 = 20*math.log10(1/math.sqrt(mse))
    return psnr2
 
imag1 = cv.imread("dian.jpg")
print (imag1.shape)
heif_file = pyheif.read("dian.heic")
imag2 = Image.frombytes(
    heif_file.mode, 
    heif_file.size, 
    heif_file.data,
    "raw",
    heif_file.mode,
    heif_file.stride,
    )

res1 = psnr1(imag1,imag2)
print("res1:",res1)