I want to move a viewing window over an image (from top to bottom) in 6 seconds. For instance, I have a grey image (500*500px), the window will replace this grey image with another image (e.g., a face). Observers will see that the moving window is revealing the face part-by-part. However, as the window moves downward, the top part of the image which is "outside of the window" is again replaced by the grey image.
I was thinking 'for loop' the image to create the window, 'if' to replace the image, but not sure how to make it move downwards while replacing the previous pixels with the original grey image.
Thanks for the help! Appreacite it!