Illustration for the puzzle game "Family Mystery - The Story of Amy".
Unlike most hidden objects games, where items are just haphazardly tossed around, the items in here are drawn into the line art and the result is almost like an optical illusion.
There are about twelve of them in every single image and there are thirty picture in the game.
Here is a link to the site where you can download and try it - one hour - for free.[link]