> ## Documentation Index
> Fetch the complete documentation index at: https://docs.runchat.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Edit only a specific region of an image

> Draw a box mask in a code node and add or change things inside it without touching the rest of the render

When only one part of a render needs to change, mask it. Everything outside the mask stays pixel-identical, so you can add details without the model re-imagining the whole scene.

![A street render, a black box mask over the corner shopfront, and the render with a cafe awning and tables added](https://mintcdn.com/runchat/ExzxwftWKPCOoCF3/images/examples/editing-a-region.webp?fit=max\&auto=format\&n=ExzxwftWKPCOoCF3\&q=85\&s=94ff804c89ce1b8dff9049ddd8d94d13)

> [card] [Open the example workflow](https://runchat.com/editor?id=e71ca75a-86aa-44ce-bb8e-b79cac9b9d3d)
>
> Make a copy of this workflow in your account to try it with your own images.

## How it works

1. **Render to edit** holds the image.
2. **Region mask** is a short code node that draws a black rectangle (the area to edit) on white at the render's size. Change its box values to move the region.
3. **Edit masked region (Ideogram 4.5)** fills the box from the prompt: *add a deep green canvas cafe awning above the corner shopfront, with small round marble cafe tables…*

## Tips

* Make the box a little larger than the thing you're adding so it has room for shadows.
* For irregular areas, paint a mask in the [image editor](https://docs.runchat.com/concepts/editor/image-editor.md) instead, or capture one from Rhino ([masks by material](https://docs.runchat.com/examples/masks-by-rhino-material.md)).


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