I’ve spent a lot of time in my column talking about text processing and analysis, with the basic assumption that if you’re using the command line, you’re focused on text. That’s not always true, and if you work with images at all—whether JPEG, PNG, GIF or another format—there’s a free-to-download suite of image-related utilities available that offers rather amazing capabilities direct from the command line and, therefore, also from within shell scripts.
I’m talking about ImageMagick, a set of programs that has grown and expanded through the years and now includes powerful Perl and Ruby interfaces too.