Remove "artifical ring" from microscope

Hello,
I’m trying to remove a ring artifact from my IX81 microscope and was wondering whether anyone knows of any good ways through ImageJ to do this. Any help is appreciated!

#File
05perc_10x_6_PH.TIF (8.0 MB)

#Screenshot

Thanks!!

Hi @williampangbest1,

the best option by far would be to check if the microscope is set up correctly and if the vignetting artifact has something to do with either the aperture diaphragm or if simply the camera system or tube does not fit to the microscope.
Since the latter would mean investing in new equipment and I assume that might not be possible on the short run the 3 next best alternatives are:

  1. cut the part in the middle as shown below or a little bit smaller:

This might lead to data loss at the borders

  1. run a pseudo-flat-field correction by using the BioVoxxel Toolbox

But since the vignetting artifact is so extreme, you will not be able to get rid of it completely.

  1. Potentially, FFT-filtering could help as well
run("Bandpass Filter...", "filter_large=40 filter_small=3 suppress=None tolerance=100 autoscale saturate");

Here, just a trial without much optimization (but it includes a histogram normalization, meaning contrast adjustment):

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