http://www.cs.cornell.edu/courses/cs664/2003fa/images/
- internet/set1

http://www.math.umbc.edu/~rouben/2003-09-math625/images.html
- internet/set2

http://orion.math.iastate.edu/burkardt/data/pbm/pbm.html
http://orion.math.iastate.edu/burkardt/data/pgm/pgm.html
http://orion.math.iastate.edu/burkardt/data/ppm/ppm.html
http://orion.math.iastate.edu/burkardt/data/pnm/pnm.html
(Some of the PNM files are bad: values exceed maxval.)
- internet/set3


http://upload.wikimedia.org/wikipedia/commons/b/b6/SIPI_Jelly_Beans_4.1.07.tiff
SIPI.tiff