[ Thanks to Lee Schlesinger for this link. ]
Want a powerful, scriptable bitmap image editor that
creates, edits, and converts images? ImageMagick is a suite of 11
commands and a GUI that let you manipulate pixel-based images and
supports more than 100 image file formats.ImageMagick is a useful tool for webmasters who need to create
web photo galleries, resize images and create thumbnails, and
automatically resize user-uploaded images.