Here's a new use for your imaging expertise:
http://www.icingimages.com/

To make a long story short, is the trick is to use the special "icing" paper?

BTW: Our local Safeway bakery offers "picture cakes."

"Edible FDA approved inks are required for creating safe edible images. All of our products are Kosher and Parve. Our edible ink cartridges are designed specifically for use in certain Canon bubble-jet printers. We offer refillable ink kits, and cleaning cartridges. We use sugar based paper which allow for the best merging on the market, they do not have a funny taste and are easy to cut once merged on to the cake."