There are computer programs, like Extensis Portfolio, which make
tracking these things less onerous. And releases for use are going
to vary widely depending on the provenance of the image in
consideration.
But in some sense a project like that really isn't analogous to the
music sampling issue. The tiled montages I know are composed of
recognizable images, even when printed in a medium sized coffee
table book, as long as one looks with some attentiveness.
And if you use images from the big two- Corbis or Getty - they will
get out a magnifier and check them out and be on your case in a
moment.
--
Emily L. Ferguson
mailto:elf@xxxxxxxx
508-563-6822
New England landscapes, wooden boats and races, press photography
http://www.vsu.cape.com/~elf/