Controllable inpainting Gaussian blur sigma value

[catboxanon]

Closes #1811

This exposes the Gaussian blur sigma value used for inpainting (currently hardcoded at an arbitrary value of 7), which can allow for a more smoother transition in some cases, especially for txt2img outpainting. The default value remains at 7.

You can see a before/after comparison here: https://imgsli.com/MTkzMzYw
(image from #1597 (comment))

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I believe this could still be improved but I'm not sure the best way to go about implementing a proper fix. An additional final pass in img2img + manual feathering may be the only way to 100% resolve it for the time being.

cc @wywywywy if you would like to test this out as well.

[huchenlei]

LGTM on moving hard-coded number 7 to config. 👍

[wywywywy]

Just tested it, and this works very well. Thank you so much.

Value of 30+ seems optimal for outpainting, while for actual inpainting 10 is pretty good.

So what would make it even better, is for this to become a generation parameter in my opinion.

[catboxanon]

I consider the parameter a bit more experimental to control and also not 100% a proper fix, so I didn't want to make it a generation parameter. If a proper fix were implemented at some point then it could certainly live there imo.

[aulerius]

Is it possible to experiment and overwrite this parameter through API calls?
I'm always having visible seams when outpointing via API manually using inpaint_only.

From left to right: ControlNet input, mask, and output.

[catboxanon]

Passing it into the override settings of the API call like this should work.

"override_settings": {
	"control_net_inpaint_blur_sigma": 14
}