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?

>>5
We don't mind if you spend time on imageboards, we mind if you import memes from there. /prog/ memes are also stupid and should be discouraged.