Manually selecting a denoise profile adjusts a[0] parameter

Is there an existing issue for this?

• I checked and did not find my issue in the already reported ones

Describe the bug

When I open an image in the darkroom, darktable correctly finds the ISO and loads a camera-specific profile. (I'm using an OM-1 Mark ii.) It displays "found ISO 2500" (for example) in the profile field of the "denoise (profiled)" module. If I click on that field and manually select "OM-1 Mark II iso 2500", then in the history stack it shows that a[0] has changed from -1.0 to 0.0001, as shown in the attached screenshot. Looking in the profiles database, 0.0001 is what is recorded there. So it looks like the "found ISO 2500" profile is not setting a[0] correctly.

Steps to reproduce

1. Open a raw image in darkroom.
2. In denoise (profiled) module, click on the "found ISO xxx" line and select " iso xxx".
3. In the history stack, it shows that a[0] has changed.

Expected behavior

a[0] should be the same for both.

Logfile | Screenshot | Screencast

Commit

No response

Where did you obtain darktable from?

OBS build

darktable version

5.4.1

What OS are you using?

Linux

What is the version of your OS?

Ubuntu 24.04

Describe your system

No response

Are you using OpenCL GPU in darktable?

Yes

If yes, what is the GPU card and driver?

No response

Please provide additional context if applicable. You can attach files too, but might need to rename to .txt or .zip

Reproducible on a fresh edit. Reproducible with a new config dir. No lua scripts.

Start by reproducing the issue with a raw image in the darkroom and the denoise (profiled) module, using a fresh config directory if needed. Compare the automatically found ISO 2500 profile with the manually selected camera profile, then inspect the profile database and history stack; done means both paths leave a[0] unchanged.