I have a FITS file initially stacked by DSS called Autosave. If I crop in Siril 1.4.0Beta4 it appears that an older version or something else replaces the image on screen. Its hard to explain, so I recorded the desktop. Is this a bug or something else?
There is no bug here, this is working as expected. Your initial image has completely different statistical characteristics to the cropped image - primarily the big black borders. When you crop it the black borders are gone, so the distribution of pixel values is different. Autostretch mode computes its autostretch parameters every time the image is updated. (In this respect I think it’s possibly somewhat different to the STF in PixInsight, though I’m not really familiar with that software.) Anyway, all you are seeing is the different autostretch computed based on different distributions of pixel values in the original and cropped images. If you use a different preview mode (sqrt might be enough, or log) then the area will look the same in the original and cropped image as those preview modes are not dynamic - log (pixel value) is always the same.
This doesn’t affect the real data, it’s just a preview so you can see details in the image more easily while it is still linear. The real “human visible” result is when you apply a specific stretch (asinh, histogram, GHT, statistical stretch, curves or a combination of the above) and when you do that you should be in Linear preview mode so as to see the true result of your stretch.
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Thank you ajeb78 for the response, you are 100% correct. Its so strange that I’ve worked on many images and never noticed this before, thank you. 