A simple freeware program for creative painting. Includes a highly configurable brush system and built-in teamwork features.

This program for photographers and imaging enthusaists offers new and unique presets and filters for transforming digital photos into amazing works of art. It can be used as a standalone product or as a Photoshop plug-in.

Please note: Use of the Windows version requires a two-stage online registration during installation. Mac users need to install the trial version and use the contact form to send the text "c’t Digital Photography – Color projects for MAC" to the manufacturer. You will then recieve a free serial number via email.

Registered readers also qualify for a 40% discount on upgrades to a full version of 'PHOTO WORKS projects #3'. Registration and upgrade offers apply until March 31st 2016.

A semi-professional, open source image processing software suite that includes layer support and a wide range of correction tools and filters. A user guide is available here.

The portable version of the semi-professional, open source GIMP image processing software suite that includes layer support and a wide range of correction tools and filters. Runs directly from USB or other memory media and requires no additional installation. A user guide is available here and you can download the source code here.

A plug-in for GIMP that contains a large number of predefined image filters and effects. The source code is available for download here.

Please note: The contents of the archive have to be copied to the GIMP plug-ins folder, which can usually be found under C:\Programs\GIMP-2.x\lib\gimp\2.0\plug-ins\. The G'MIC entry will be listed in the GIMP Filter menu when you restart the program.

A comprehensive image and icon editing software package. Requires Java Runtime Environment (JRE) 5.0 or higher to run.

A comprehensive suite of tools for stitching horizontal and vertical panoramas. Automatically generates control points that can be manually adjusted by the user. The source code is available for download here. Requires .NET Framework 3.5 or later.

An open source vector graphics editor with capabilities similar to Illustrator, CorelDraw, or Xara X. Uses the W3C standard scalable Vector Graphics (SVG) file format. Inkscape supports many advanced SVG features (markers, clones, alpha blending, etc.) and makes it easy to edit nodes, perform complex path operations, trace bitmaps and much more. The source code is available for download here.

Luminance HDR is a graphical user interface (based on Trolltech's Qt4) that provides a workflow for HDR imaging. Supports HDR, TIFF, PFS or EXR, as well as JPEG, PNG, PPM, PBM and TIFF LDR images. You can download the source code here.

Simple-to-use image-processing software with a wide range of tools and functions for optimizing digital images. The software offers manual and fully automated adjustments and the 'Cut Out' tool for removing unwanted objects and backgrounds.

Please note: c’t Digital Photography readers can register via e-mail for a free copy of Movavi Photo Editor. Windows users click here for a 40% discount on a purchase of Movavi Photo Studio. Mac users click here for a 60% discount on Movavi Video Converter. These offers are valid until January 15th 2016.