change contrast brightness of image

contrast.py

#cv2.addWeighted(source_img1, alpha, source_img2, beta, gamma)
alpha = [0.75, 0.5, 0.25]
beta =  [0, 1 , 10]
gamma = [0, 10 ,100]

#Vary alpha
alpha_img1 = cv2.addWeighted(rgb_img, alpha[0], rgb_img, beta[0], gamma[0])
alpha_img2 = cv2.addWeighted(rgb_img, alpha[1], rgb_img, beta[0], gamma[0])
alpha_img3 = cv2.addWeighted(rgb_img, alpha[2], rgb_img, beta[0], gamma[0])

#Vary beta
beta_img1 = cv2.addWeighted(rgb_img, alpha[0], rgb_img, beta[0], gamma[0])
beta_img2 = cv2.addWeighted(rgb_img, alpha[0], rgb_img, beta[1], gamma[0])
beta_img3 = cv2.addWeighted(rgb_img, alpha[0], rgb_img, beta[2], gamma[0])

#Vary gamma
gamma_img1 = cv2.addWeighted(rgb_img, alpha[0], rgb_img, beta[0], gamma[0])
gamma_img2 = cv2.addWeighted(rgb_img, alpha[0], rgb_img, beta[0], gamma[1])
gamma_img3 = cv2.addWeighted(rgb_img, alpha[0], rgb_img, beta[0], gamma[2])