SSIM
A C++ implementation of SSIM (structural similarity). Home page : http://www.cns.nyu.edu/~lcv/ssim/
The source file (won't work without OpenCV) : SSIM.cpp
Zip package containing a MSVC6 project, with ready-to-use binaries : SSIM.zip
DSSIM
A fork was made by Philipp Klaus Krause to compute DSSIM (Structural Dissimilarity). For more info, see http://colecovision.eu/graphics/DSSIM/