The picture of the ants on a Moebius strip was made from a wood engraving of M. C. Escher. A rather poor scan of the original can be viewed as a 123K gif or a 93K jpeg.
The golden spheroid (well, it is supposed to be golden) is made from a photograph published by RIT News and Events, May 18, 1993. The statement "R(4,5)=25" is the title of a paper I wrote with Stanislaw Radziszowski for the Journal of Graph Theory.
The ostrich picture was made from a photograph by the Mexican photographer Col. Manuel Romero, ca. 1870. A scan of the original photograph can be viewed as a 232K gif or a 41K jpeg. It comes from the book Retratos de Mexicanos 1939-1986, Fondo de Cultura Economica 1991.
