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Re: median filter that preserves peaks

Posted by Neil Fazel on Sep 08, 2013; 7:03pm
URL: http://imagej.273.s1.nabble.com/median-filter-that-preserves-peaks-tp5004693p5004721.html

Thanks for the responses.

It seems to me that a generalized spatial filter (e.g. the "XXXFilter" suggested by Kenneth) might be the way to go.

I did give FFT a try and, after tweaking the parameters, got results matching what the median filter produced. However, it seems to me that one needs to be careful with FFT filtering. Sometimes high frequency components of the signal are noise and need to be removed. Sometimes they are actual signal and removing them biases the data. In such cases, a spatial filter such as mean or median may be appropriate. For example, in my case, I have x-ray which is filtered by Cu or Al and recorded on an imaging plate. What looks like noise could in fact be from sideways scattering of x-rays inside the filter pack. One needs to determine whether such signal should be removed (via FFT filter) or merely smoothed (via mean or median filter) to make analysis easier.

Regards,
Neil

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