Puzzle# is a simple library for comparing the visual likeness of images. The algorithm used and library implementation is partly based on fragments from projects such as image-match for Python and libpuzzle for C.

Conceptually, the library accepts an arbitrary image and produces a perception hash of the visual contents, which can then be compared to other signatures to determine how closely matched the two images are. It should be noted that this algorithm is not one that detects conceptually similar visual works; rather, it is suited for comparing edited, recoloured, watermarked, or damaged images - detecting copyright violations, for example, would be an appropriate use case.

Get it on NuGet or compile from source.