darktable is an open source photography workflow application
ImageMagick 7
Library to encode and decode images in WebP format
A fast image processing library with low memory needs
A collection of packages providing extra functionality for GNU Octave
Scanning probe microscopy data visualisation and analysis
Swiss army knife of image processing
Lynkeos is an astronomical webcam image processing software for OS X.
Batch Image Rename, Slideshow, Convert, Resize in Windows Context Menu
ProStack - a platform for image processing and analysis
Astronomical object/structure detection from 1D and 2D data sets.
Resilient Image Library - successor to DevIL
Image processing library in C/C++
Tools to access streams in PDF-files at the object level.
Collection GIMP plugins by zvezdochiot
Easy converting pgm and ppm to (MASK+FG+BG)-djvu.
Easy converting PNM to (MASK+FG+BG)-pdf.
Libraries and command line tools for medical image processing.
Graphic Live Mixer
Digital image processing programs for Windows and Linux systems.
Some image processing tools