image processing question

Why isn't there a way to search for images by drawing a rough outline of a part of the image and returning all images that roughly match that outline?

I know edge detection algorithms aren't perfect but surely someone has thought of this - so why hasn't Google made this already?

This would be great. Sometimes I'm on the imageboards (don't judge me, k) and I get sidetracked. Now I'm doing other shit like shitposting on /prog/ and fapping to hentai. I decide to switch to the imageboard tab (don't judge me, k) and the thread was already pruned. Now how the fuck am I going to find that reaction image? With OP's invention, of course! Submit that shit to Y-Combinator and Paul Graham will make you rich.