Nobody has mentioned imagemagick?! Good god!
Well, yes, actually, the article's author did.
Finally, your editor will respond grumpily to mail suggesting packages like netpbm or ImageMagick. Those tools are invaluable for scripted applications, and no doubt some clever netpbm hacker could devise a six-stage pipeline involving two separate invocations of the ppmfrobnicate filter to perform all of the tasks above. That is not interesting, however; image viewing and editing is are jobs best done in a graphical mode.
I guess you can await a grumpy reply.
Copyright © 2017, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds