This program is part of Netpbm.

pnmscale was obsoleted by pamscale,introducedwithNetpbm10.20 (Jan-
uary 2004). pamscale is backward compatible with pnmscale, plus adds
many additional functions, including the ability to process PAM
images, and tends to produce better results.

pnmscale remains in the current Netpbm package because it probably has
fewer bugs for now than pamscale, and may have superior performance
characteristics in some cases. Some day, pnmscale will probably
become an alias for pamscale.

You can use the pamscale documentation for pnmscale, considering the
following differences:

? pnmscale options are a subset of pamscale's, as

? pnmscale always assumes the input is linear, as pamscale

? pnmscale cannot process PAM images.

netpbm documentation 25 January 2004 Pnmscale User Manual(0)