Re: median filter that preserves peaks
Posted by
Alexandre Dufour on
Sep 06, 2013; 10:25pm
URL: http://imagej.273.s1.nabble.com/median-filter-that-preserves-peaks-tp5004693p5004711.html
Dear Neil,
From a purely signal processing perspective, I suggest you use Fourier- (or better off wavelet-) denoising on such signals. They definitely should preserve your signal dynamics. A good illustration in 1D is given over here (
http://www.mathworks.fr/products/demos/shipping/bioinfo/mspreprodemo.html#22)
Alexandre
---
Alexandre Dufour, Ph.D.
Institut Pasteur - Quantitative Image Analysis Group
25, rue du Docteur Roux, Paris, France
Research:
http://www.bioimageanalysis.org/dufourSoftware:
http://www.bioimageanalysis.org/icyOn Sep 6, 2013, at 11:18 PM, Neil Fazel <
[hidden email]> wrote:
> Thanks. I will look into that.
>
> I have attached a montage of 3 profile plots using 1) the original image, 2) image after applying median filter with radius 0.5, and 3) image after median filter with radius 1. You can see how the Y axis maximum of the plots goes from 3.28 to 3.15 to 3.13; the high frequency component has been reduced (good) at the same time that the peaks have been flattened (bad).
>
> I guess what I'm looking for is a filter that replaces local outliers (i.e. outliers in a neighborhood 2-3 pixels in each direction) with the median, but preserves them if they remain outliers in a larger neighborhood, which indicates that they are not noise but actual peak signal.
>
> Neil
>
>
> --
> ImageJ mailing list:
http://imagej.nih.gov/ij/list.html> <median filter flattens peaks somewhat.png>
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