InvokeAI/docs/features/INPAINTING.md

# **Creating Transparent Regions for Inpainting**

Inpainting is really cool. To do it, you start with an initial image
and use a photoeditor to make one or more regions transparent
(i.e. they have a "hole" in them). You then provide the path to this
image at the dream> command line using the `-I` switch. Stable
Diffusion will only paint within the transparent region.

There's a catch. In the current implementation, you have to prepare
the initial image correctly so that the underlying colors are
preserved under the transparent area. Many imaging editing
applications will by default erase the color information under the
transparent pixels and replace them with white or black, which will
lead to suboptimal inpainting. You also must take care to export the
PNG file in such a way that the color information is preserved.

If your photoeditor is erasing the underlying color information,
`dream.py` will give you a big fat warning. If you can't find a way to
coax your photoeditor to retain color values under transparent areas,
then you can combine the `-I` and `-M` switches to provide both the
original unedited image and the masked (partially transparent) image:

```
dream> man with cat on shoulder -I./images/man.png -M./images/man-transparent.png
```

We are hoping to get rid of the need for this workaround in an upcoming release.

## Recipe for GIMP

[GIMP](https://www.gimp.org/) is a popular Linux photoediting tool.

1. Open image in GIMP.
2. Layer->Transparency->Add Alpha Channel
3. Use lasoo tool to select region to mask
4. Choose Select -> Float to create a floating selection
5. Open the Layers toolbar (^L) and select "Floating Selection"
6. Set opacity to 0%
7. Export as PNG
8. In the export dialogue, Make sure the "Save colour values from
   transparent pixels" checkbox is selected.