Hello all. I’m an absolute beginner with ImageJ/Fiji. I’ve been able to apply a few useful built-in tools to my CT scans, but many of the filters fail or get thrown off because my images have a background (that clearly contains no information). The kind of images I look at can be found here: https://blog.highmarkhealth.org/low-dose-ct-scans-show-promise-in-detecting-early-stage-lung-cancer/lungcancer. As you can see, anything outside the inscribed circle is useless background.
My question to the community is: How do you suggest I get rid of this background? Can I do this using the existing functions, or do I have to write my own script or plug-in? (additional detail that may be of help: for my purposes, it would be OK to merge the background with the dark, textured parts at the top and bottom of the disk.) One idea, suggested by a community member, would be to generate a circular ROI covering the area of interest and nothing else, and then do the filtering on that. But the ROI would be specific to (and thus would have to be generated automatically for) each scan, and even each slide of the 3D scan. Any suggestion on how to do that? Thanks a lot in advance! -JF