Purpose
This is an ImageJ plugin for denosing images via the non-local-means algorithm described in
including the changes proposed by
It is numerically optimized and multithreaded. It works with all image types (RGB, 32 Bit, 16 Bit, 8 Bit).
This plugin was developed within the scope of a study work of Pascal Behnel and is maintained by Thorsten Wagner (Both are members of the Biomedical Imaging Group).
Settings
Sigma: The sigma of the noise.
Smoothing factor: In most cases, the default value (1) should not be changed. However, sometimes a more smoothed image is desired which can be achieved by selecting values > 1.
Auto estimate sigma: If this option is selected, the sigma is automatically estimated by the method descriped in Immerkaer, J., 1996. Fast noise variance estimation. Computer Vision and Image Understanding.
Both, the value for the (estimated) sigma and the smoothing factor are saved in the imagej preferences and are accessible with the keys “nlmean.sigma” / “nlmeans.smoothingfactor”.
Example
The left image shows a noisy (sigma=25) image, and right image the denoised version using the non local means plugin with auto-estimated sigma and smoothing factor of 1:
Installation
You could simply use our update site “Biomedgroup” to install the non local means plugin, or copy the jar file into your plugins folder.
How to cite
We think the best way is to cite the formal method and the used implementation:
Method:
Implementation:
