Blender AgX in darktable (proof of concept)

Eary_Chow · September 13, 2025, 4:46pm

Well

s7habo · September 13, 2025, 4:48pm

Check out the video in this post:

priort · September 13, 2025, 4:50pm

I just built it now and I can confirm that if you do a module reset at least on Windows you get the unmodified default as the reset condition not the intial scene referred default that is applied to the image on import or module activation…

Eary_Chow · September 13, 2025, 4:50pm

Well, if it needs manual toggling, it’s not really a default anymore.

I think that setting is supposed to set the default active picture formation module, like picking whether you want Filmic RGB or AgX to be active by default, not the default preset for the module. It’s kind of weirdly dependent.

priort · September 13, 2025, 4:55pm

I think its a bug… in darkroom if you open a new image with agx as the setting in preferences you get the scene-referred preset. If you make an edit and then do a module reset it goes to unmodified. If you reset from original in the history stack it behaves properly so for me it the module reset that is not going back to the right default and I think once before updating my build I saw that unmodified was the highlighted default so maybe this got left in the code for the reset??

s7habo · September 13, 2025, 5:20pm

This is because we now have three active image formation options and people can choose one of them.

Once you have set this, all photos that you import into darktable or clear the history will have this new selected workflow.

Photos that were previously edited/imported will retain the old workflow. This ensures that previous edits remain intact.

If, for whatever reason, you reset the module’s parameters, you can restore the default values by pressing Ctrl+reset button:

Eary_Chow · September 13, 2025, 5:23pm

I mean, the default preset for the module should not be interrelated with which module is active by default. Even when Filmic rgb is the default active module, AgX module’s own default preset should still not be unmodified base primaries .

s7habo · September 13, 2025, 5:26pm

I agree. That’s definitely the bug.

g-man · September 13, 2025, 5:27pm

I’m not at the PC anymore for a while. Can you try with a new darktablerc (to test)?

PD1 · September 13, 2025, 5:32pm

On windows 11, I have set the processing to SR (Agx). When I load a new picture the AgX module chooses "unmodified base primaries (default) " and not the “scene-referred default” So I have to take the extra step to change and then start the other work. This is the problem

priort · September 13, 2025, 5:41pm

I think you hit on it…the “default” is not really “scene referred default” (see below). That setting is acting like or being applied as if it were an autopreset even though you cannot appear to edit it as one and so if you use ctrl reset it will come back to that group of settings…If you just do a plain module reset then it goes to the values for defaults that are still in the code and that is the unmodified ones…So what the true “defaults” are should be clarified…at least this is how its working for me…but I also in going back and forth have a new issue…DT has started applying both sigmoid and agx to my image with the workflow set AGX. I am going to look in my darktablerc file to see if I can see anything… You can see compressing the stack and then resetting it applies both tonemappers

Now if I set the worflow to filmic or agx I get that module plus sigmoid. I checked in my darktablerc file and the correct setting seems changed there and I have tried opening and closing DT before trying again…

I will be curious to see if this happens to anyone… I think while testing I did a control - compress in the history stack and after this it started…

s7habo · September 13, 2025, 6:03pm

I think this is because one of your Sigmoid presets is set to apply to all photos. This conflicts with the given workflow, which in this case is AgX.

Try turning off the “auto apply this preset for matching images” option in the settings for the given preset for Sigmoid (Slider boast).

priort · September 13, 2025, 6:06pm

Thanks funny I had been testing agx before and never noticed that behaviour…I wonder if there was a small difference in the master and Kofa’s branch …thanks for the eagle eye detective work…

Edit ha stupid me no mystery I was running AGX parallel to my install which has my presets and AGX testing did not…thanks again that was not on my radar…

RawConvert · September 13, 2025, 6:17pm

I’m finding Pivot Target Output is rather sensitive to mouse movement. It goes 0 to 100% at present. Is it possible to make it 0 to 50? That’s still quite a range, and of course it’s easy to increase the limit if you need >50.

kofa · September 13, 2025, 6:55pm

Sorry, I was on the phone, and only quickly read messages. You are correct, not having scene-referred default is strange. The AppImage is Darktable-5.3.0+339.gbe20d249c3-x86_64.AppImage, and the commit for the scene-referred preset comes before that in the commit log, 85db9495.

Is your workflow setting set to scene-referred (agx) in preferences? The preset is only created if your selected workflow is that one.

github.com/darktable-org/darktable

src/iop/agx.c

737e214bc


      
          const gboolean auto_apply_agx = strcmp(workflow, "scene-referred (agx)") == 0;
          
          if(auto_apply_agx)
          {
            // The scene-referred default preset
            p.curve_contrast_around_pivot = 2.8f;
            p.curve_toe_power = 1.55f;
            p.curve_shoulder_power = 1.55f;
            p.look_power = 1.f;
            p.look_offset = 0.f;
            p.look_saturation = 1.f;
          
            dt_gui_presets_add_generic(_("scene-referred default"),
                                       self->op, self->version(), &p, sizeof(p),
                                       TRUE, DEVELOP_BLEND_CS_RGB_SCENE);
          
            dt_gui_presets_update_format(BUILTIN_PRESET("scene-referred default"),
                                         self->op, self->version(),
                                         FOR_RAW | FOR_MATRIX | FOR_HDR);
            dt_gui_presets_update_autoapply(BUILTIN_PRESET("scene-referred default"),

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I’ll look into the reset logic to see how I can get AgX to return to the preset after it has been reset. Thanks for reporting. I can confirm that Ctrl+reset works, but reset does not, while for exposure and filmic reset works, too.

kofa · September 13, 2025, 6:58pm

I don’t understand what you mean. For me, both dragging the sliders and using the mouse wheel work fine.

Eary_Chow · September 13, 2025, 7:01pm

This is the weird logic I am talking about. This means if the user is having the default filmic rgb workflow setting on, and they just want to play around with the new module, they manually turn filmic rgb off, and they turn on AgX, they will see unmodified base primaries by default.

Like I said, the default preset for the module should not depend on which module is active by default. AgX module’s own default preset should not be unmodified base primaries, even when Filmic rgb is the default active module.

g-man · September 13, 2025, 7:05pm

Lets give it 24hr until the bug is resolved. I think we all agree that the module default should have the agx primaries.

RawConvert · September 13, 2025, 7:46pm

I mean a small mouse movement causes quite a large change to the image. It’s a coarse adjustment.
However it seems I’ve got out of the habit of using the mouse wheel on sliders! - this does give a finer adjustment.
So I think it’s ok with the 100% limit.

kofa · September 13, 2025, 7:55pm

I honestly don’t feel it’s coarse. The slider followed my mouse, and the image changed gradually. Is your experience different?