python Histogram Test program

gistfile1.txt

import cv2
import numpy as np
import random
from matplotlib import pyplot as plt
from matplotlib.backend_bases import NavigationToolbar2

# https://opencv-python.readthedocs.io/en/latest/doc/19.imageHistograms/imageHistograms.html#mask
# https://opencv-python-tutroals.readthedocs.io/en/latest/py_tutorials/py_imgproc/py_histograms/py_histogram_equalization/py_histogram_equalization.html
# https://opencv-python-tutroals.readthedocs.io/en/latest/py_tutorials/py_imgproc/py_histograms/py_histogram_begins/py_histogram_begins.html

img1 = cv2.imread('/usr/share/scratch/Media/Backgrounds/Outdoors/village.jpg',0)

hist1 = cv2.calcHist([img1],[0],None,[256],[0,256])
hist2 = cv2.calcHist([img1],[0],None,[128],[0,128])
hist3 = cv2.calcHist([img1],[0],None,[128],[128,256])

hist4,bins = np.histogram(img1.ravel(),256,[0,256])

print "hist4-128 %d" %(hist4[128])
print "hist1-128 %d" %(hist1[128])
#print "hist2-128 %d" %(hist2[128])
#print "hist2-129 %d" %(hist2[129])
#print "hist2-140 %d" %(hist2[140])

plt.subplot(221),plt.imshow(img1,'gray'),plt.title('Red Line')
plt.subplot(222),plt.plot(hist1,color='r'),plt.title
plt.subplot(223),plt.plot(hist2,color='g')
plt.subplot(224),plt.plot(hist3,color='b')
plt.xlim([0,256])

plt.show()