Rendering of images in linear mode changes significantly in brightness with GraxPert

Hi,

I’ve been using GraxPert in SIRIL and it works great, but I’ve run into an image rendering artifact in SIRIL. When I run GraxPert denoise on a stretched image, the image background will often get much darker. But the statistics shows it to be about the same mean.

When I “undo” he denoise, it gets light again and then I “redo” the denoise and now the background is light, as it used to be and the statistics is the same. This appears to be an issue with how SIRIL is rendering the image for on screen. I have no profile on the image and the min/max parameters at the bottom of the window are at their normal maximum positions.

I can post images if you need, but this nearly always happens (perhaps always happens) with GraxPert denoise: Image background gets rendered much darker even though the statistics (mean or R, G, or B) don’t change much.

OK, I found the issue. Whenever I run GraxPert the image “min” slider next to the profile indicator at the bottom always snaps over to the right about 10%, but when I undo and then “redo” it, it’s now snapped back to the left at 0. This is really strange behavior, can someone explain why this is happening and can I force SIRIL just to leave those sliders alone? I don’t want it to always be changing those sliders on me when I’m trying to edit an image.

Forgot to note some details:

SIRIL 1.4.2
Windows 11
Files are 32-bit .FITs background corrected and stretched in linear view mode.