residual layer in retouch wavlet decomposition differs between opencl and cpu

[MStraeten]

Describe the bug

deactivating gpu processing results in a darkened residual layer

opencl on:

opencl off:

Steps to reproduce

1. show residual layer in retouch
2. enable/disable opencl

Where did you obtain darktable from?

self compiled

darktable version

windows: 4.9.0+1227gbb12aceef5
macos: 4.9.0+1229gfabbd1d450

What OS are you using?

Windows
also reproducible on macos

What is the version of your OS?

Win 10, MacOS1 5

Describe your system?

Prozessor 13th Gen Intel(R) Core(TM) i7-1365U 1.80 GHz
Installierter RAM 32,0 GB (31,7 GB verwendbar)

apple m1max

Are you using OpenCL GPU in darktable?

Yes

[jenshannoschwalm]

Can you say if this is something new.

[MStraeten]

unfortunately not, reproducible even with my 4.8.1 build ...

[jenshannoschwalm]

unfortunately not, reproducible even with my 4.8.1 build ...

In a way - good for me as i was sure not introducing a regression by late code mods.

[MStraeten]

side note: the different handling on cpu path seems to be consistent with the behaviour described in #8894 (but there it's consistent dark for gpu and cpu path)

a wavelet decomposition in gimp is similar to the gpu behaviour

[jenshannoschwalm]

I checked the code and it's at least not something obvious. So no fix for 5.0 unfortunately. We should come back to this and your other issue report.