pngcrush is an excellent batch-mode compression utility for PNG images. Depending on the application that created the original PNGs, it can improve the file size anywhere from a few percent to 40% or more (completely losslessly). The utility also allows specified PNG chunks (e.g. text comments) to be inserted or deleted, and it can fix incorrect gamma info written by Photoshop 5.0 as well as the erroneous iCCP chunk written by Photoshop 5.5.
ImgView is a simple image viewer for Unix-like systems. It is free from menus and other GUI gadgets, and controlled primarily by the keyboard. It supports the following image file formats: XBM, PBM/PGM/PPM, GIF, JPEG, TIFF, PNG, and PCX. It supports RGB, Gray, and CMYK ICC profiles in JPEG, RGB and Gray ICC profiles in TIFF and PNG, and RGB ICC profiles in GIF.
Orfeo Toolbox (OTB) is a high resolution remote sensing image processing library. It contains a set of algorithmic components which allow the user to capitalize on methodological know how, and therefore use an incremental approach to profit from the results of methodological research. OTB is made of a set of basic elements (a C++ class API) and utilities (independent programs built upon the base API).
Asciidia generates bitmap or vector files from simple ASCII diagrams. It was inspired by ditaa but has a plugin based architecture, which allows it to draw specialized diagrams. Currently-supported diagram types are simple ASCII diagrams and directory trees. Asciidia can directly output SVG and MVG. For additional file formats, an ImageMagick installation is required.
Calligra is an integrated suite of applications that cover office, creative, and management needs. It offers applications on both desktop computers and mobile platforms like tablets and smartphones. OpenDocument Format (ODF) is used, making it compatible with OpenOffice.org, LibreOffice, and Microsoft Office. Calligra Suite contains the following applications: Calligra Words (word processor), Sheets (spreadsheets), Stage (presentations), Flow (diagrams and flowcharts), Kexi (visual database creator), Braindump (note taking), Plan (project management), Krita (drawing), and Karbon (vector graphics).
Lynkeos processes astronomical webcam images. By stacking the best images, the signal to noise ratio is increased, and details lost in the noise of individual images become visible in the resulting image. This software accepts, as input, QuickTime, AVI, and MPEG sequences, or still images, in any image format supported by its active plugins (TIFF, FITS) and Cocoa. It generates a 16-bit RGB TIFF or a monochrome FITS image as output, to be further processed with some all-purpose image processing application.