def main():
imagePath = "img.jpg"
img = cv2.imread(imagePath)
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
generate_histogram(gray)
cv2.imwrite("before.jpg", gray)
gray = cv2.equalizeHist(gray)
generate_histogram(gray)
cv2.imwrite("after.jpg",gray)
return 0