import cv2 import numpy as np from matplotlib import pyplot as plt file0 = 'image.jpg' img = cv2.imread(file0) color = ('b','g','r') plt.figure() for i,col in enumerate(color): histr = cv2.calcHist([img],[i],None,[256],[0,256]) plt.plot(histr,color = col) plt.xlim([0,256]) plt.show()