To compare the raw processors I chose a rather “difficult” raw file. So, how do the candidates shape up? As well as considering which features are available in each, we should also consider ease of use and general impressions of the GUI, and perhaps most important, the quality of the finished image. Output file format – as well as jpeg for projection or web use, a lossless format such as tiff.Monochrome conversion – not simply by desaturation.Sharpen – by use of unsharp mask, possibly other options.Denoise – to reduce noise effects in low light shots and/or use of high ISO settings.Vignette – either to correct the effect of lens vignetting or to introduce a vignette for artistic reasons.

Lens correction – geometry (pincushion and barrel distortion) and Chromatic Aberration.The basic adjustments – exposure, white balance, levels and curves, saturation etc.Colour management – ability to handle input and output colour profiles and to select a working colour space.I regard the following capabilities as essential: I have used both RawTherapee and Darktable for over a year and have recently tried Lightzone and Photivo so I will restrict my comments to these four. I don’t expect to print directly from the raw processing application though this might be an advantage. I am looking for a raw file processor that will allow me to develop raw images to produce files ready for projection (at 1400 x 1050 pixels) and files at full resolution for further development, as necessary, to make high quality prints. With the exception of Darktable, which is not yet available for Windows, all of the applications are available for Windows, Mac and Linux. This article was first published in January 2014 and represents my views at that time. A comparison of four free raw file processors: RawTherapee, Darktable, Lightzone and Photivo.

Darktable or rawtherapee