Suppose I have a grayscale image, i.e. each pixel in this image has a value between 0 and 255.

I want to know what this image will look like at a distance z from the source. I know that Fresnel and Fourier transforms can and should be used to do this, but I don’t know how to do it from a programming point of view.

I’m just starting to understand optics, so I may be expressing myself incorrectly, but I hope the concept is clear. Ready for more questions!