[AI] Add raster mask export for object masks

[andriiryzhkov]

Another small improvement. Not 100% sure about it, but maybe helpful for someone.

Adds the ability to export the SAM segmentation mask as an RGB PNG file, compatible with the external raster masks module. Triggered by shift+right-click during object mask creation.

How it works

• Shift+right-click saves the raster mask as PNG, then applies the vectorized mask as usual
• Right-click (without shift) applies the mask normally, no file saved
• Zero friction for the default workflow – no extra config or UI elements

Output format

• RGB PNG (R=G=B=mask value) compatible with the rasterfile IOP module
• Binary mask: 255 for foreground, 0 for background (uses the same threshold as vectorization)
• Saved to the raster mask root folder configured in Preferences → Processing → "raster mask files root folder" (plugins/darkroom/segments/def_path)
• Filename: {image_name}_mask.png, auto-incremented (_1, _2, ...) if file exists

[TurboGit]

Frankly I'm not sure if it is useful or not. I certainly won't use this, but that's only me. I cannot come with a scenario where this will be handy at the moment.

[deekayhd]

Frankly I'm not sure if it is useful or not. I certainly won't use this, but that's only me. I cannot come with a scenario where this will be handy at the moment.

If I understand correctly, this would allow to have a more precise mask than the vectorized mask (e.g. for rugged edges).

[andriiryzhkov]

Not sure, if there will be any quality benefits. Vectorisation is pretty accurate if you keep smoothing at 0. Maybe at some edge cases.

But that adds dependency on an external file. So pipe willing work correctly without it.

[deekayhd]

Not sure, if there will be any quality benefits. Vectorisation is pretty accurate if you keep smoothing at 0. Maybe at some edge cases.

Ok, never mind. I thought this a mitigation for what was discussed in this posting on pixls.us
https://discuss.pixls.us/t/testing-ai-object-masks-in-darktable-nightly-builds/56684/27?u=deekay

[andriiryzhkov]

Frankly I'm not sure if it is useful or not. I certainly won't use this, but that's only me.

Me too. But I saw people asking about it. And it's not a big feature, so decided to propose it. We can keep it for later if there will be more requests.

[andriiryzhkov]

@deekayhd :

I thought this a mitigation for what was discussed in this posting on pixls.us

It is exactly for that purpose. Just not sure if it will help much with fine details on edges. But idea is that it might be useful for someone.

[TurboGit]

Ok, let's go with this. Thanks.

[TurboGit]

@andriiryzhkov : Seems like there is an issue with this PR. For a reason I cannot understand I cannot merge this. GitHub tells me that the branch is not properly sync. When I pull the branch directly from your repo I have 2 commits.

Can you force push the branch again? TIA.

[andriiryzhkov]

@TurboGit :

Can you force push the branch again?

Done