GMIC

GMIC is an open-source framework for image processing. GMIC (Greyc's Magic for Image Computing) is a complete framework for image processing. It is popular for being combined as plugin for GIMP to process images. GMIC gives GIMP more than hundreds of image filters. The plugins is also able to manage multi-layers inputs and outputs.  It provides several different user interfaces to convert / manipulate / filter / visualize generic image datasets, ranging from 1d scalar signals to 3d+t sequences of multi-spectral volumetric images, thus including 2d color images. GMIC also provides a powerful and autonomous command-line interface that can be used in ImageMagick or GraphicsMagick projects.