Thread: Pyramid (Scheme) Sharpening..Why it just might work

I can think of a horrible mathematical explanation. If you add up a sequence of sine waves in the right way, you can approximate a square wave - i.e. flat top:



This is a bit like what you are doing when you are adding up rough and smooth scratch patterns. Not sure you can read too much into this - if you add them in the wrong proportions you end up with a sawtooth pattern instead.