We'll also need some images to work with. Here are a few (you can also use photographs you have taken, or images you find on the web):
3blks1.png
shapes2.png
allblcks.png
bcrbohsp.png
512test2.png
boulder.png
wave-cld.png
calcium.png
fngrprnt.png
Bikesgray.png
Che_GS.png
faces1.png
zebras.png
penguins.png