Raspberry Pi 3 Cookbook for Python Programmers - Third Edition

How to do it…

1. Import the necessary packages:

import sys 
import cv2 
import numpy as np 

2. Load the input image:

in_file = sys.argv[1] 
image = cv2.imread(in_file) 

3. Convert the RGB image into grayscale:

image_gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY) 
cv2.imshow('Input grayscale image', image_gray) 

4. Regulate the histogram of the grayscale image:

image_gray_histoeq = cv2.equalizeHist(image_gray) 
cv2.imshow('Histogram equalized - grayscale image', image_gray_histoeq) 

5. Regulate the histogram of the RGB image:

image_yuv = cv2.cvtColor(image, cv2.COLOR_BGR2YUV) 
image_yuv[:,:,0] = cv2.equalizeHist(image_yuv[:,:,0]) 
image_histoeq = cv2.cvtColor(image_yuv, cv2.COLOR_YUV2BGR) 

6. Display the output image:

cv2.imshow('Input image', image) cv2.imshow('Histogram ...