subplot(rows,cols,plot_number) #行、列、窗口序号
import cv2
import numpy as np
import matplotlib.pyplot as plt
img = cv2.imread('./bomb.jpg',cv2.IMREAD_GRAYSCALE)
equ = cv2.equalizeHist(img)
plt.subplot(121),plt.hist(img.ravel(),256)
plt.subplot(122),plt.hist(equ.ravel(),256)
plt.show()