How to compare histogram in real time with camera?

Question

I try this code for detecting object histogram realtime with the camera and its work :

import cv2
import numpy as np 
from matplotlib import pyplot as plt

camera = cv2.VideoCapture(1)

base1 = cv2.imread('base1.png')
base2 = cv2.imread('base2.png')
base3 = cv2.imread('base3.png')

#Set hist parameters
hist_height = 64
hist_width = 256
nbins = 32
bin_width = hist_width/nbins
hrange = [0,180]
srange = [0,256]
ranges = hrange+srange                            # ranges = [0,180,0,256]

#Create an empty image for the histogram
h = np.zeros((hist_height,hist_width))

while 1:
    grabbed, img = camera.read()
    cam = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    if not grabbed:
      "Camera could not be started."
      break

    histcam = cv2.calcHist([cam], [0], None, [nbins], [0,256])
    cv2.normalize(histcam,histcam, hist_height, cv2.NORM_MINMAX)
    hist=np.int32(np.around(histcam))

    for x,y in enumerate(hist):
        cv2.rectangle(h,(x*bin_width,y),(x*bin_width + bin_width-1,hist_height), (255), -1)

    #Flip upside down
    h=np.flipud(h)

    #Show the histogram
    cv2.imshow('Color Histogram',h)
    h = np.zeros((hist_height,hist_width))

    cv2.imshow('img',img)
    k = cv2.waitKey(30) & 0xff
    if k == 27:
        break

camera.release()
cv2.destroyAllWindows()

and I add this code under the code above to compare the histogram :

#Compare the Histogram

base1hsv = cv2.cvtColor(base1,cv2.COLOR_BGR2HSV)
base2hsv = cv2.cvtColor(base2,cv2.COLOR_BGR2HSV)
base3hsv = cv2.cvtColor(base3,cv2.COLOR_BGR2HSV)

histbase1 = cv2.calcHist([base1hsv], [0], None, [nbins], [ranges])
cv2.normalize(histbase1,histbase1,hist_height,cv2.NORM_MINMAX)
hist=np.int32(np.around(histbase1))

histbase2 = cv2.calcHist([base2hsv], [0], None, [nbins], [ranges])
cv2.normalize(histbase2,histbase2,hist_height,cv2.NORM_MINMAX)

histbase3 = cv2.calcHist([base3hsv], [0], None, [nbins], [ranges])
cv2.normalize(histbase3,histbase3,hist_height,cv2.NORM_MINMAX)

for i in xrange(1):

    if i == 0 :
        print ("Correlation", cv2.HISTCMP_CORREL)

    base1_base1 = cv2.compareHist(histbase1,histbase1, cv2.HISTCMP_CORREL)
    base1_cam = cv2.compareHist(histbase1, histcam, cv2.HISTCMP_CORREL)
    base2_cam = cv2.compareHist(histbase2, histcam, cv2.HISTCMP_CORREL)
    base3_cam = cv2.compareHist(histbase3, histcam, cv2.HISTCMP_CORREL)
    print "Method: {0} -- base1-base1: {1} , base1-cam: {2} , base2-cam: {3} , base3-cam: {4}".format(cv2.HISTCMP_CORREL, base1_base1, base1_cam, base2_cam, base3_cam)

the code can run without error but print method result not displayed on the terminal? whats wrong with my code?

you probably need to flush the stdout, [look at this question](https://stackoverflow.com/questions/230751/how-to-flush-output-of-print-function) for a possible solution — api55, Jul 10 '18 at 07:29
that is not another way to print to the terminal, sometimes it is in a buffer and does not shows until a lot of text has been written to it or that the program exits... this just will get that buffer written immediately (just write it after the print) — api55, Jul 10 '18 at 09:50
I guess a Debugger would help to clear your confusions about the course of execution of your script. Use a Debugger to see if your `print` statements are reachable? — ZdaR, Jul 10 '18 at 11:05

How to compare histogram in real time with camera?

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