The Netpbm PAM documentation suggests that I will have a fairly seamless transition if I choose to start using PAM instead of PPM/PGM/PBM as an image format:
"PAM" is in fact a fourth format. But it is so general that you can represent the same information in a PAM image as you can in a PBM, PGM, or PPM image. And in fact a program that is designed to read PBM, PGM, or PPM and does so with a recent version of the Netpbm library, will read an equivalent PAM image just fine and the program will never know the difference.
[Updated: 09 October 2005 ]
Note: The above comment is also included in
man pam on the systems that I am having trouble with.
However, when I run Netpbm utilities on Ubuntu (several versions including 12.10), it does not work as advertised:
$ pnminvert P7 pnminvert: bad magic number - not a ppm, pgm, or pbm file
I have verified that some other distributions, as well as from-source builds of netpbm-super-stable (also stable, advanced), do not have this problem.
It looks like from the packages page, that this package is being updated periodically, so I can't figure out why the Ubuntu versions wouldn't work.
I want to deploy tools based on this to an arbitrarily large number of machines, so build-from-source isn't appealing. Any ideas about how to make this work on Ubuntu?