ImageMagick 7
A fast image processing library with low memory needs
darktable is an open source photography workflow application
Library to encode and decode images in WebP format
Swiss army knife of image processing
Lynkeos is an astronomical webcam image processing software for OS X.
Tools to process and visualize scientific data and images
ProStack - a platform for image processing and analysis
Image processing library in C/C++
Resilient Image Library - successor to DevIL
Open Source Solid Modeling CAD
Drawing, graphics conversion, software development, administration.
Convert Netpbm programs to GIMP plug-ins
LDraw™ editor for LEGO® style digital building instructions.
Tools to access streams in PDF-files at the object level.
Easy converting pgm and ppm to (MASK+FG+BG)-djvu.
Collection GIMP plugins by zvezdochiot
Extend abcm2ps to support direct generation of PNG, SVG and PDF files
Scanning Probe Microscopy Controller and Data Visualization Software
Improved JPEG encoder
Rayshade raytracer