Jade is a cross-platform diagram editor built on the Qt framework.
FNT Font editor
sauerbraten with LuaJit2 scripting
Not your usual Architectural Modeler
Output Processing script from Java AWT/Swing paint call
An open-source cross-platform digital painting / image editing app
Just a Tiny, VERY Tiny app that uses the mposplit command app to work
Command line image editing software package and libraries.
A powerful C++ class library for image manipulation