The topic is image compression. Here are some links.
http://www.met.reading.ac.uk/~unix-doc/docs/jpeg.html - A page with examples of how to use the JPEG compression libraries.
http://www.cs.sc.edu/~culik/valenta/ - This page has general data compression links.
http://www.image.cityu.edu.hk/imagedb/ - A database of commonly used images for compression testing.
http://www-isl.stanford.edu/~gray/shorterlBVQ.pdf - A paper about image compression.