Lynkeos is an astronomical webcam image processing software for OS X.
Earth orbits and satellite coverage display in 3D on your laptop.
ProStack - a platform for image processing and analysis
Astronomical object/structure detection from 1D and 2D data sets.
A scientific plotting library for C/Fortran built on cairo
Cross-platform open source software for astrophotography
Siril is an astronomical image processing software for Linux.