Hands-On Image Processing with Python

Using non-local means

Non-local means is a non-linear denoising algorithm that preserves textures. In this algorithm, for any given pixel, a weighted average of values of only those nearby pixels that have similar local neighbors as the pixel of interest are used to set the value of the given pixel. In other words, small patches centered on the other pixels are compared to the patch centered on the pixel of interest. In this section, we demonstrate the algorithm by denoising a noisy parrot image using the non-local means filter. The h parameter to the function controls the decay in patch weights as a function of the distance between patches. If h is large, it allows more smoothing between dissimilar patches. The following code block shows ...