Python如何绘制直方图hist的详细步骤？

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pythonimport matplotlib.pyplot as pltimport argparseimport cv2import numpy as np

def calcAndDrawHist(image, c): # 省略具体实现 pass

import sys
sys.path.append('/usr/local/lib/python2.7/site-packages')
sys.path.append('/usr/lib/python2.7/dist-packages')
import matplotlib.pyplot as plt
import argparse
import utils
import cv2
import numpy as np

def calcAndDrawHist(image, color):
hist= cv2.calcHist([image], [0], None, [256], [0.0,255.0])
minVal, maxVal, minLoc, maxLoc = cv2.minMaxLoc(hist)
histImg = np.zeros([256,256,3], np.uint8)
hpt = int(0.9* 256);

for h in range(256):
intensity = int(hist[h]*hpt/maxVal)
cv2.line(histImg,(h,256), (h,256-intensity), color)

return histImg;

if __name__ == '__main__':
img = cv2.imread("c.jpg")
b, g, r = cv2.split(img)

histImgB = calcAndDrawHist(b, [255, 0, 0])
histImgG = calcAndDrawHist(g, [0, 255, 0])
histImgR = calcAndDrawHist(r, [0, 0, 255])

cv2.imshow("histImgB", histImgB)
cv2.imshow("histImgG", histImgG)
cv2.imshow("histImgR", histImgR)
cv2.imshow("Img", img)
cv2.waitKey(0)
cv2.destroyAllWindows()