Why is the 'Median Filter' limited to a radius of 100 pixel maximum?

Posted by Matthias Schade on Dec 15, 2014; 7:29pm
URL: http://imagej.273.s1.nabble.com/Why-is-the-Median-Filter-limited-to-a-radius-of-100-pixel-maximum-tp5010953.html

Hello

it is not possible to execute the 'Median Filter' nor the 'Remove Outliers..' function via user-interface for radii > 100 pixels. Historically, considering processing power or RAM this might have been a reasonable limit. But nowadays?

I was following recommendations from the following paper on the inference of an illumination function where the authors apply a median filter (r=500 pixels) on an image of 1280x1024 pixels:
Singh, S., Bray, M., Jones, T. R., & Carpenter, a E. (2014). Pipeline for illumination correction of images for high-throughput microscopy. Journal of Microscopy, 256(3), 231–6. doi:10.1111/jmi.12178

The ImageJ java code which I think is responsible for catching any radius>100 pixel is found in "RankFilters.Java" (latest version for 1.49m) and states: "int maxRadius = (filterType==MEDIAN || filterType==OUTLIERS || filterType==REMOVE_NAN) ? 100 : 1000;"

This limitation is void/ignored for ImageJ macros, i.e. using a line such as: run("Median...", "radius=200 slice");

Cheers
Matthias

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Matthias Schade

Humboldt-Universität zu Berlin
Molekulare Biophysik  -  Institut für Biologie
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