I heard of filtering algorithms which, to filter an image specific area, find similar areas in the image and average them to reduce the noice of the original area. E.g. an edge of a house can be more or less the same in the whole image, so one can make many patches from that area and average them. It should be similar to using multiple shots of the same scene and averaging them to make a final image.
What's this algorithm called? I'd like to learn more about it as I found it pretty interesting. But couldn't find them on the Internet so far except some general averaging algorithms.