========
pnmcurve
========

apply tone curves to pnm images.
Curves are specified as a set of control points of a cubic spline.
pnmcurve applies the resulting spline curve to the pnm image read
from stdin and writes the resulting image to stdout.
The -rgb command line switches allow to apply the curve only to
selected color channels.

pnmcurve is intended to be used with the flimp 
(http:www.ecademix.com/JohannesHofmann/flimp.html), but can also be 
used as a standalone filter.