RGB (scene) by default in masks blending options if scene-referred is the default workflow.

[difrkaguilar]

Is your feature request related to a problem? Please describe.
Every time I create a mask in a module, then I've to select RGB (scene) in blending options too, others modules like Color calibration and color balance rgb have this option selected by default. I think that maybe some modules aren't optimized for the new scene-referred workflow. But It's suposed that if in darktable preferences the default workflow is selected as scene-referred, then all modules, optimized or not must change their masks blending options to RGB (scene)

Describe the solution you'd like
If scene-referred is selected as default workflow, then all masks blending options in modules must be RGB (scene) by default too.

Additional context
two sample images
Lab selected by default.

RGB (scene) by default.

[jmoric]

@TurboGit : To get this right. Should all modules be set to use RGB color space by default in scene-referred workspace. Apart from RAW modules of course.

That is int default_colorspace(...) return IOP_CS_RGB in scene-referred workspace. Even if they are not optimized to use RGB color space?

[TurboGit]

@jmoric : I'm not sure about all the implications. Some module are Lab should we use RGB (display or scene-referred).

Let's ping @flannelhead who knows lot more about color than me.

[ralfbrown]

I don't think just having default_colorspace always return IOP_CS_RGB will work properly, since it provides the module's expected input colorspace and produced output colorspace when input_colorspace or output_colorspace are not implemented. The pipeline code then uses that information to insert colorspace conversions as needed to adapt the output of one module to the input of the next.

In the specific case of contrast equalizer, that module operates in Lab, so using an RGB blend mode implies a colorspace conversion before the blending. The module happens to be in a position in the pipe where the following module is probably expecting RGB input, in which case a conversion would be needed either way. But if the following modules expect Lab input, an RGB blend mode adds two conversions.

(BTW, that reminds me that I want to raise an RFC about changing colorin's output colorspace from Lab to RGB, since it will almost certainly be followed by a module taking RGB input.)

[jmoric]

I don't think just having default_colorspace always return IOP_CS_RGB will work properly, since it provides the module's expected input colorspace and produced output colorspace when input_colorspace or output_colorspace are not implemented. The pipeline code then uses that information to insert colorspace conversions as needed to adapt the output of one module to the input of the next.

Yes, it also seemed way too easy considering this problem has been delayed since 2021 (milestone 3.8). Thanks for the explanation.

In the specific case of contrast equalizer, that module operates in Lab, so using an RGB blend mode implies a colorspace conversion before the blending. The module happens to be in a position in the pipe where the following module is probably expecting RGB input, in which case a conversion would be needed either way. But if the following modules expect Lab input, an RGB blend mode adds two conversions.

(BTW, that reminds me that I want to raise an RFC about changing colorin's output colorspace from Lab to RGB, since it will almost certainly be followed by a module taking RGB input.)

@ralfbrown : To summarize: We should leave this as is until further module interface decisions are specified.

[jenshannoschwalm]

There has been done some work on module colorspace so we might want to check again about this idea.