Comma Coloring

These types of things should replace CAPTCHA's

I doubt very many people are going to take the time to draw out these pictures on an ongoing basis, so you'll have to continually market to new people who will try it out once, or you'll have to pay people to do it. Wouldn't it be better for you to take a best guess at highlighting a region and then simply ask people to confirm? For example, you'd show two pictures, one with the original and one with your best guess of the sky highlighted and ask "Is this highlight of the sky accurate, yes or no?".