Wikipedia
RawTherapee is a cross-platform raw image processing program, released under the GNU General Public License Version 3. It was originally written by Gábor Horváth of Budapest, Hungary, before being re-licensed as free and open-source software in January 2010. It is written in C++, using a GTK+ front-end and a patched version of dcraw for reading raw files. It is notable for the advanced control it gives the user over the demosaicing and developing process. The name used to stand for "The Experimental Raw Photo Editor"; however that acronym has been dropped, and RawTherapee is now a full name in itself.
RawTherapee comprises a subset of image editing operations specifically aimed at non-destructive raw photo post-production and is primarily focused on improving a photographer's workflow by facilitating the handling of large numbers of images.