Non-Local Means Filter | 555Tools — Online Tools for FPGA & Algorithm Engineers

Image AlgorithmsTool Introduction

Non-Local Means (Buades et al. 2005) differs fundamentally from local filters: for each pixel, it traverses all candidates in the search window and assigns weights based on the similarity (Gaussian-weighted Euclidean distance) between the candidate patch and the center patch. Textured and repeating structure regions receive high weights, achieving better denoising with texture preservation than bilateral/Gaussian filters. The patch similarity concept is a watershed in the denoising family.

Key Formula / Principle

NLM(p) = sum_q w(p,q)*I(q) / sum_q w(p,q)
w(p,q) = exp(-||P(p)-P(q)||^2 / h^2)
Patch distance: Gaussian-weighted SSD over patch pixels

Data Processed Locally|All computations run in your browser. Images, formulas, state machine definitions, and any other input data are never sent to any server.

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