KNLMeansCL is an optimized OpenCL implementation of the Non-local means de-noising algorithm. The NLMeans filter, originally proposed by Buades et al., is a very popular filter for the removal of white Gaussian noise, due to its simplicity and excellent performance. The strength of this algorithm is to exploit the repetitive character of the image in order to de-noise the image unlike conventional de-noising algorithms, which typically operate in a local neighbourhood.
For end user KNLMeansCL is a plugin for AviSynth, AviSynth+ and for VapourSynth. Windows, OS X and Linux are supported. Read more on the Wiki and support on the Doom9 forum.
KNLMeansCL is available under the GNU GPL v3 license.