> For the complete documentation index, see [llms.txt](https://know.rendernetwork.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://know.rendernetwork.com/docs/prepare-your-scene/exr-and-dwa-compression.md).

# EXR output and DWA compression

Choose EXR precision and compression for compositing, including when to use DWAA, DWAB, ZIP, or PIZ.

## Keep a linear image for compositing

EXR preserves a wide range of brightness values, including bright highlights. **32-bit** EXR stores these values more precisely than **16-bit** EXR. See the [OpenEXR technical introduction](https://openexr.com/en/latest/TechnicalIntroduction.html).

For Octane Standalone or Cinema 4D with Octane, leave **Tonemapped** off and choose the required **Color Space** in the job's [output configuration](/docs/web-app/outputs.md) for linear EXR compositing. For Blender and Redshift, prepare colour management in the source scene; the web app does not offer a colour-space override for those outputs.

Use the same [OCIO view](/docs/prepare-your-scene/ocio.md) in your compositor when comparing the EXR with your local render preview.

## Choose compression

Lossless compression keeps the image values unchanged. Lossy compression can make files smaller by changing some of those values.

| Compression        | Choose it when                                                                                                     |
| ------------------ | ------------------------------------------------------------------------------------------------------------------ |
| **ZIP** or **PIZ** | You need lossless compression that preserves the image values.                                                     |
| **DWAA**           | You accept lossy RGB compression and your workflow often reads only part of a frame.                               |
| **DWAB**           | You accept lossy RGB compression and usually read complete frames. It is generally more space-efficient than DWAA. |

OpenEXR's [compression reference](https://openexr.com/en/latest/StandardAttributes.html) describes the differences.

Render and download a representative frame before committing to DWA for a delivery. Check fine detail, smooth gradients, and the result of your intended grade in the compositing application that will receive the files.


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