python 直方图hist

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()