计算图像照片直方图 python opencv

import cv2
from matplotlib import pyplot as plt
import os
import numpy as np
filepath = './Input'
pathDir = os.listdir(filepath) 
for allDir in pathDir:
    picpath = r'./Input/' + allDir
    pc = cv2.imdecode(np.fromfile(picpath, dtype=np.uint8), 0) 
    plt.hist(pc.ravel(),256,[0,256]) 
    plt.suptitle(allDir[:-4],fontsize = 20,color ='black')  
    plt.savefig(allDir)  
    plt.close() 
    print('\n','运行结束！直方图在当前目录下……')