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Snyder's book has a wealth of information about map projections,
but if you expect to pick it up and write yourself a few quick
programs to do the conversions, you'll be in for a rude awakening.
You are much better off using an existing library of transformations
than to try and reinvent the wheel.  These operate typically on
the "actual" data (lat/long, UTM, Albers, etc.) rather than on pixels
on your screen, though.  From ftp://charon.er.usgs.gov/pub/PROJ.4
you can get information on PROJ4, as well as the programs, courtesy
of USGS.
 
Nick Reddingius    BBN Systems and Technologies   (818) 226-0356
21120 Vanowen Steet -- Canoga Park, CA 91303 -- [log in to unmask]