import cv2 
import numpy as np

def show_image(img):
    cv2.imshow("image", img)
    cv2.waitKey(0)
    cv2.destroyAllWindows

zdj = cv2.imread("kebab.jpg", cv2.IMREAD_COLOR_RGB)

def reverse(img):
    new_img = []
    for row in range(img.shape[0]):
        new_row = []
        for column in range(img.shape[1]):
            new_row.append(img[-1-row][column])
        new_img.append(new_row)
    return np.array(new_img)


for row in range(zdj.shape[0]):
    for col in range(zdj.shape[1]):
        B = zdj[row][col][0]
        G = zdj[row][col][1]
        R = zdj[row][col][2]
        zdj[row][col][1] = R*0.2 + G*0.2 + B*0.2

show_image(zdj)