Images: lena, mandril, boat, peppers
Origin - The USC-SIPI image database
http://sipi.usc.edu/database/database.cgi?volume=misc

Images: goldhill
Origin - PNG library
http://www.libpng.org/pub/png/pngmisc.html

Images: lorikeet (Rainbow Lorikeet)
Origin - Simon Fenney (c)
http://web.onetel.net.uk/~simonnihal/3d.html

Image: Monarch
Origin - University of Waterloo, Waterloo Fractal Coding and Analysis Group
http://links.uwaterloo.ca/bragzone.base.html