Repository: stable-diffusion-webui
Issue: [Bug]: Inpaint thinks black background is part of the mask
Labels: bug-report

### Is there an existing issue for this?

- [X] I have searched the existing issues and checked the recent builds/commits

### What happened?

I take an image that was created with txt2img, modified with inpainting, then modified with an image editor (Photopea) before being put back into Inpaint. It happens to have a large area that is `#000000` total black. When I try to inpaint part of the image, it includes much of that black background as if it was part of the mask. When in the image editor I add `#010000` to remove the black background then the problem goes away. Therefore it seems that inpainting treats `#000000` pixels as if they were part of the mask.

### Steps to reproduce the problem

1. Go to Inpaint
2. Load an image with a black background like https://www.mediafire.com/view/j6t1kfqan8tk2wb/15360-black_background.png/file
3. Inpaint literally anything, like say a hand
4. Select `Only masked`
5. See how the black background area is included
6. Do the same with an image with no black background like https://www.mediafire.com/view/mqddujgu07godfi/15360-red_background.png/file
7. See how only the masked area is included

Pic is what happens with the black background when only the hand is inpainted
![2023-03-03 14 41 00](https://user-images.githubusercontent.com/7466235/222735093-de69d7c2-387c-40c6-8aaf-50809aeca121.png)


### What should have happened?

Pic is what happens with the `#010000` background when only the hand is inpainted (same everything as the previous screenshot).
![2023-03-03 14 41 36](https://user-images.githubusercontent.com/7466235/222735198-532311ae-9f86-48a2-acdb-3f8113623fff.png)


### Commit where the problem happens

https://github.com/AUTOMATIC1111/stable-diffusion-webui/commit/0cc0ee1bcb4c24a8c9715f66cede06601bfc00c8

### What platforms do you use to access the UI ?

Windows

### What browsers do you use to access the UI ?

Google Chrome

### Command Line Arguments

```Shell
--medvram --opt-split-attention --skip-torch-cuda-test --opt-sub-quad-attention
```


### List of extensions

<html>
<body>
<!--StartFragment-->

Extension | URL | Version | Update
-- | -- | -- | --
openpose-editor | https://github.com/fkunn1326/openpose-editor.git | cc742cb8 (Mon Feb 27 23:26:31 2023) | unknown
sd-webui-controlnet | https://github.com/Mikubill/sd-webui-controlnet | 3a1c5b9f (Mon Feb 27 19:57:39 2023) | unknown
LDSR | built-in |   |  
Lora | built-in |   |  
ScuNET | built-in |   |  
SwinIR | built-in |   |  
prompt-bracket-checker | built-in |   |  

<!--EndFragment-->
</body>
</html>

### Console logs

```Shell
venv "C:\msys\home\sd\sd\venv\Scripts\Python.exe"
Python 3.10.6 (tags/v3.10.6:9c7b4bd, Aug  1 2022, 21:53:49) [MSC v.1932 64 bit (AMD64)]
Commit hash: 0cc0ee1bcb4c24a8c9715f66cede06601bfc00c8
Installing requirements for Web UI

Launching Web UI with arguments: --medvram --opt-split-attention --opt-sub-quad-attention
No module 'xformers'. Proceeding without it.
Loading weights [03df69045a] from C:\msys\home\sd\sd\models\Stable-diffusion\stablydiffuseds_26.safetensors
Creating model from config: C:\msys\home\sd\sd\configs\v1-inference.yaml
LatentDiffusion: Running in eps-prediction mode
DiffusionWrapper has 859.52 M params.
Loading VAE weights specified in settings: C:\msys\home\sd\sd\models\VAE\vae-ft-mse-840000-ema-pruned.safetensors
Applying sub-quadratic cross attention optimization.
Textual inversion embeddings loaded(2): bad_prompt_version2, bottomless_embed
Model loaded in 10.8s (load weights from disk: 0.3s, create model: 1.2s, apply weights to model: 6.6s, apply half(): 1.9s, load VAE: 0.7s).
Running on local URL:  http://127.0.0.1:7860

To create a public link, set `share=True` in `launch()`.
  9%|███████▊                                                                           | 3/32 [00:14<02:16,  4.71s/it]
Total progress:   0%|                                                               | 3/3200 [00:12<3:44:59,  4.22s/it]
100%|██████████████████████████████████████████████████████████████████████████████████| 32/32 [02:34<00:00,  4.83s/it]
100%|██████████████████████████████████████████████████████████████████████████████████| 32/32 [02:37<00:00,  4.91s/it]
 97%|███████████████████████████████████████████████████████████████████████████████▍  | 31/32 [02:33<00:04,  4.91s/it]
Total progress:   3%|█▊                                                            | 95/3200 [07:45<4:14:00,  4.91s/it]
```


### Additional information

_No response_