Digital Image Processing Using Python & OpenCV

Using OpenCV library in Python 3.6 to apply auto-contrast to a grayscale image.

import numpy as np
import cv2

imgloc="C:/Users/ASUS/Desktop/images/abgs1.jpg"
img=cv2.imread(imgloc,0) #0 for grayscale ,1 for color, -1 for alpha channels(png)

height=img.shape[0]
width=img.shape[1]

min=255   #While comparing if any pixel value<min we set it to min
max=0      #While comparing if any pixel value>max we set it to max

for i in np.arange(height):
    for j in np.arange(width):
        a=img.item(i,j)  #Getting the pixel value
   
        if a>max:
            max=a
        if a<min:
            min=a

for i in np.arange(height):
    for j in np.arange(width):
        a=img.item(i,j) 
        b=float(a-min)/(max-min)*255     #By proportion b:255=(a-min):(max-min)
        img.itemset((i,j),b)
imgloc="C:/Users/ASUS/Desktop/images/abautocontrast.jpg"
cv2.imwrite(imgloc,img)
cv2.imshow('image',img)     #'image' is our window name
cv2.waitKey(0)  #waits indefinitely for a keystroke
cv2.destroyAllWindows()


Original Image:

Image after running above code: