I’ve introduced the free Gimpel3D manual 2D to 3D stereo conversion software here on the blog back in 2011, and now the author has made it an open source software by releasing the code of the project on Sourceforge. Gimpel3D is a free application that can help you convert a single 2D image or image sequence into stereoscopic 3D written by René Gimpel. The conversion to 3D is manual and the software only assists you, so do not expect automation like with an 2D to 3D autoconversion solutions that do everything with just a click of a button, with Gimpel3D however you can get much better results.
Since the original freeware release of Gimpel3D, many of the ideas presented in the software have become standard features in commercial software and as a result the author of the program has decided that there is no significant advantage to continue developing it as a stand-alone proprietary solution, although the codebase makes a nice platform for future research and experimentation. René Gimpel has released all source code for G3D under the GPL so that other stereo researchers, hobbyists, and/or professionals can build upon his existing work, and integrate/test new capabilities using the projective modeling environment.