Description
Is there an existing issue for this?
- I checked and did not find my issue in the already reported ones
Describe the bug
Is this module really working as expected?
If I enable it on any photo, then set Contrast boost to an arbitrary "high" number...
(anything in the range 20 to 100 shows the effect clearly).
Then, the Sharpness setting is not creating a linear adjustment, it changes ONLY at specific points among the adjustment.
I'd expect it to behave as Contrast boost which seems to be "linear".
ALSO: I have issues in using masking to block this filter (e.g. have it NOT act on light tones, especially with Contrast enhancing mix modes).
as #16706
Steps to reproduce
Enable it on any photo and then, for a quick assessment:
Set the Contrast to 30-ish...
Stepping Sharpness from 0 up to 5, noting dramatic happens,
but as you get past 5 there is a dramatic effect (more precisely at 5.24 to 5.26 ).
A similar increased effect appears as you step from 24 to 25.
With the eyes on the histogram, you see there is something similar at stepping from 42 to 43
Again, 49 to 50 - the image changes again.
More: 74 to 75 - image change again.
80 to 81, another histogram change.
Expected behavior
Contrast setting should be linear, not "discrete" in this stepwise manner.
Logfile | Screenshot | Screencast
Highpass_C@5.24
Highpass_C@5.26
Commit
No response
Where did you obtain darktable from?
darktable.org / GitHub release
darktable version
5.2 and earlier
What OS are you using?
Linux
What is the version of your OS?
Ubuntu 24.04.2 LTS Pro-ESM, x86_64
Describe your system
A few years old Asus G731 Laptop
Are you using OpenCL GPU in darktable?
Yes
If yes, what is the GPU card and driver?
NVIDIA GeForce GTX 1660 Ti, Driver Version: 550.144.03 CUDA Version: 12.4
Please provide additional context if applicable. You can attach files too, but might need to rename to .txt or .zip
No response
NOTE: This has been present in several of the recent DT versions, most certainly from at least a few years back.