[feature request] Adding an extra control for the Feather size in Inpainting

[Dartasia]

Hi ^-^,

First I wish to thank you for all the hard work and dedication you have been putting into this awesome plugin!

I was thinking about the idea/feature for users to have the ability of controlling the Feather size via a second slider (or allow the slider to reduce the Feather size as well since we can only increase it at the moment) as I've noticed that since v1.46.0 and 1.46.1 that the inpainting has been unable to reproduce the same range we used to be able to produce. I've included a few examples. The first image is the original result (if my memory is correct it was 1% Extra inpainting, 3% or 5% Blend and 1% Extra padding.

Here is the original v1.45.0 (at 70% Denoise) :

The below images are with version 1.46.1 (at 70% denoise) :

From my testing, I've concluded that Padding does not directly change the affected Inpaint area (black area in the examples) and simply allows a greater size of the image to be taken into account during generation (to help the model etc.) and also fixes the rough edges of the Feather mentioned in a previous issue.

Thus in the following examples I did not change the padding as the black area remained the same regardless of the value (but for info, it is at 1%).

Example 1 - Using the following settings : 1% Feather, 25px Blend. (This is the closest result I could make to the original with Feather On)

Example 2 - Using the following settings : 0% Feather, 25px Blend

With further testing I observed the following :

• Adjusting the Feather only increases the inpainting outside of the selected area (and still causes the hard edges unless the padding is increased to 5%+.

• Increasing the Blend above 25px tends to create a ghosting effect (the original v1.45.0 could achieve a lesser ghosting effect while retaining an area closer to the selection.

• Decreasing the Blend does allow a closer border result to v1.45 but due to the default Feather size increase (even at 1%), we cannot replicate the same accurate result as in v.1.45.0.

Extra Examples for v1.46.1 (at 70% Denoise) :

Example 3 - Using the following settings : 1% Feather, 5px Blend.

Example 4 - Using the following settings : 1% Feather, 50px Blend.

Example 5 - Using the following settings : 0% Feather, 5px Blend. (Best result to the original but we have a smaller inpainted area than the selection)

Example 6 - Using the following settings : 25% Feather, 5px Blend. (Adjusting the Padding can help prevent the edge from clipping but will not reduce the overall Feather size)

Example 7 - Using the following settings : 25% Feather, 25px Blend. (Higher Blend will only create a ghosting effect).

(Setting 0% to both Feather and Blend will result in a sharp inpainted area (visible seams etc.) that follows exactly the selection, which I assume is the correct behavior.)

With an additional slider for the Feather size we could hopefully reduce the added inpaint area to obtain a smaller border (the same result as v1.45.0).
I'm aware that at the moment the Feather adds by default a certain % by default (affected by the denoise % if I understood correctly the latest commits changes), but I think it is oversized when selecting smaller area.

General behavior of v1.46.1 based on testing :

When Feather is ON (1% and above) = Inpaints outside the selection.
When Feather is OFF (0%) = Inpaints within the selection.

When Feather is ON and Blend is ON = The border is faded out based on the Blend, but it keeps the minimal Feather area as reference thus we cannot reduce the Feather size to reproduce the original inpaint area of v1.45.0. Instead we obtain a ghosting effect when the Blend is set too high (above 25% in general)

When Feather is OFF and Blend is ON = The border can be faded out similar to v1.45.0 but it cannot exceed the inpaint area thus the accuracy of the selection is less intuitive than in v1.45.0.

Conclusion :

In the end, my suggestion is more of an ease of use for members who were more accustomed to v1.45.0, control style and I think it would be nice to have the extra slider control for the Feather area (instead of relying on a set default size).

Thank you so much for your time and consideration ✨!

[Acly]

Observations seem correct, but maybe they leave out what Feather actually does. It is represented here as uniform black area (the soft edge are just from Blend), when it's actually a linear gradient that determines how much change can happen.

Feather is used to determine the denoise mask. It is always 1.0 inside the selection, and gradually goes towards 0.0 outside of it, until what is the black area here ends completely. After that comes the padding area, which adds image context, but is never modified.

Diffusion runs in several steps, let's say you have 20. At 100% strength all 20 steps will be performed, but only where the denoise mask is 1 - ie. only inside the selection. Outside, close to the boundary of the selection, only the last 19...18...17... etc. steps are preformed, the more the mask tapers off, fewer steps will affect that area. This means less change can happen here. In particular the last few steps only allow for very minor modifications.

So while the black area might look large, it's not the same everywhere like your images might suggest. In most parts outside the selection change is limited, to integrate the new content better, but not allow significant modification.

Blend is used independently to determine the opacity mask for alpha blending (what you call "ghosting"). It is applied from the outside edge of the denoise mask (where it's almost vanished). It blurs inwards by the set blend amount of pixels.

The purpose of opacity mask is just to merge the parts where there was very little modification anyway (because denoise mask is close to 0 here) with the original image, to keep ghosting effect minimal. I think 25px is already generous, it can probably be a bit lower.

I think it makes no sense to set Blend greater than Feather - this is what allows the mask to fade inside the selection. IMO this should never happen. I want to limit the Blend so it is always equal or less than Feather. Note that this is also not really anywhere close to what was happening in older version, where you could not adjust Blend at all (only Feather).

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So much for explanation, I hope it's more clear, but I should probably make some image to explain at some point.

But regarding your request/question, the reason you can't adjust the Feather as low as you want at the moment is that there is indeed a minimum amount in absolute pixels. It's meant for small selections where the % usually doesn't work (it becomes vanishingly small).

You can open settings.json (there should be a link in plugin settings UI at the bottom). It has some more parameters:

    "selection_feather": 10,
    "selection_min_transition": 32,
    "selection_grow_offset": 4,
    "selection_blend": 25,
    "selection_padding": 6,

This is for Feather=10%, Blend=25px, Padding=6%
You can try setting selection_min_transition to 0, or some lower amount.
The default selection_min_transition=32 means feather is always at least 32px*strength, ie. 22px at 70% denoise. IMO it's a sensible value, considering most of that area will only be affects slightly, but feel free to experiment.

[Dartasia]

Thank you for your explanations and solution ^-^!