VIPS is a small, quick and memory-conservative 2D image processing C and C++ library. It comes with over 300 functions, for arithmetic processing, histograms, convolutions, morphological operations, frequency filtering, colouring, resampling, statistics and others. It supports most common raster image formats (PNG, TIFF, JPEG, FITS, OpenEXR), or chain to ImageMagick/GraphicsMagick.
Converseen is a batch image-processing application, which utilizes Qt5 for cross-platform support. It supports common image formats including DPX, EXR, GIF, JPEG, JPEG-2000, PhotoCD, PNG, Postscript, SVG, TIFF and many others. It can process single or an selectable amount of files. Converseen allows resizing, size compression, rotation and flipping, file renaming. It can also split up PDF files into multiple images.
Pngcrush is size optimizer for PNG images. It's a command-line tool, works on Unix and DOS environments. It reduces the IDAT picture data stream by testing different PNG filter methods and compression levels. It may also remove meta data chunks, or inject gAMA, tRNS, iCCP or text chunks.
G'MIC (GREYC's Magic for Image Computing) is a portable and scriptable image processing framework. It comes as C++ library, can be used as command line tool, as Gimp plugin, as web service, or with its Qt application. G'MIC allows image conversion, manipulation, applying complex filters and visualization pipelines. Various image types can be used, 1D/2D/3D sources, multi-spectral and volumetric images or 3D vector objects, regardless of pixel depths. The "gmic" command line tool is often an alte