flimp is a generic graphical frontend to the many excellent command line image manipulation tools available. It allows to create and manipulate pipelines of commands that read from standard input and write to standard output. One can view and compare the result of each stage of the pipeline. flimp leaves the input image file untouched. One rather saves the pipeline in a text file.
Also check pnmcurve a command line tone curve utility and GUI that integrates nicely into flimp.
flimp-0.0.11.tar.gz
sha1 86cd922546f78cf16757cd1c9df681b6225aadc9
A mercurial repository can be found here.
Check the README.
Changes from 0.0.10 to 0.0.11: -----------------------------