For this project students used the color replace tool from the online photo editor Pixlr. See video below for tutorial. The project is extremely simple and can offer some astonishing results.
I allowed students to choose their image, but encouraged a recognizable image from nature. Mainly because the visual impact of this edit challenge is increased when the viewer recognizes the animal or plant that is being manipulated. Black and white animals tend not to work as well as colorful ones, zebras and pandas are not the best when working in pixlr.