As a long term user of GIMP I now see a problem in how the histogram in GIMP 3.0.0 on Windows 11 is functioning. I have attached a scaled down JPG that can be used to test the out the problem.
In the unedit picture due to haze the histogram covers only a limited range. To improve this image I move the left black point triangle for the imput and this functions as expected by increasing the contrast of the image.
However, when this effect is applied and the level widows closes and then a new instance of the levels windows is open it should show a stretched histogram with a picket fence look, but it still shows the original histogram.
The correct histogram with the picket fence look can be shown by activating the histogram dialog. This is the look that should now be showing in the latest instance of levels when it is opened on the previously corrected image.
Something is not right here and I am hoping that the right people who can fix this problem see this post. The image below can be used to test this behaviour.
I think it is normal. Because, now, level adjusting module works as non-destructive filter, and the original pixel value is not changed. Picket fence look histogram must be showed only on the first level adjusting instance.
Thanks for your response. I need to research the non-destructive method of using GIMP, but the Levels tool responded in the expected ‘destructive’ way when I ticked the merge filter box.
That’s an expected reaction. If you check “Merge Filter,” the pixel value will actually (= destructively) change, and you will see a picket fence-looking histogram. If you don’t check “Merge Filter,” the actual pixel value won’t change, even though the image looks different (the filter applied non-destructively) and you will see the original histogram as before.
