GraphicsMagick provides a set of command-line applications to manipulate image files. It is a fork of the ImageMagick project and therefore offers a similar set of features, but puts a larger emphasis on stability.
The tools support a large variety of image formats from the widely used jpeg, tiff, bmp or xpm to special-purpose formats such as fits or image formats found on some photo CDs. They can convert between formats, concatenate several images into one, annotate and distort them, create thumbnails or manipulate the colormap. While all features are available from the command-line, the package also includes an image viewer that allows interactive manipulation.
Note that unlike ImageMagick, the GraphicsMagick tools are accessed through a single executable called 'gm'. Therefore, GraphicsMagick and ImageMagick can be used in parallel. Install package graphicsmagick-imagemagick-compat to obtain a set of several executables that is compatible to ImageMagick's interface.