greyscale_transform.py

#create a copy of my image
copyImg = img.copy()

#get the average of each pixel
#we need axis=2 so that we take averages accross the 3rd axis (the color axis) rather than accross the rows or columns
average_pixel_values = np.mean(copyImg, axis=2, keepdims=True)

#create the grey image by "stacking" three copies of these grey values together
greyImage = np.concatenate([average_pixel_values]*3, axis=2)

#make sure to cast the final image back to integers
greyImage = greyImage.astype(int)

#show the final image
plt.imshow(greyImage)