[Tom Ore]

I don't know the software they used but, they first digitized the pictures into a 45 x 45 grid (15 cubes with 3 squares per cube.) Then they approximated the colors with colors available on the cubes. They printed out the image on 9 sheets of paper which each had 5 x 5 grids. Each student worked from one of the sheets and solved the cubes to match.