A whole bunch of utilities for primitive manipulation of graphic images. Wide array of converters from one graphics format to another. E.g. from g3 fax format to jpeg. Many basic graphics editing tools such as magnifying and cropping.
Open Source Solid Modeling CAD
BRL-CAD is a powerful cross-platform constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing for rendering & geometric analyses, network distributed framebuffer support, image & signal-processing tools.