I've recorded a screencast of the issue here.
I have a test image that I made so I could see how various modules in Darktable effected the histogram:
I import this image in darkable and switch on shadows and highlights, this gives me a result like the below:
(not much has changed, but the bottom stripes are slightly darker)
If I then increase the exposure, everything works as I would expect (as in, the image gets lighter), until I move over about +1EV, which is when the background of the image starts to darken. By +2EV, the image looks like this:
If I switch off the shadows and highlights module - the image returns to what I would expect (more interestingly, if I switch the shadows and hightlights to bilateral filter as suggested in another thread, it works as expected as well).
My question is:
- Why does increasing the exposure of this image make it darker?
...and I wouldn't mind some context around
- Is it possible to switch on 'shadows and highlights' in a neutal state so that it doesn't change the image (like switching on crop or exposure)
- Is there a repository anywhere of more professionally generated 'see what the histogram looks like' images?
Edit - I upgraded to 3.0.2 this morning and tested again - same result.