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# auxiliaryDepth

The key into the properties dictionary indicating whether to return an auxiliary depth image.

```
static let auxiliaryDepth: CIImageOption
```

## Discussion

The value of this key is an <doc://com.apple.documentation/documentation/Foundation/NSNumber> containing a Boolean `true` or `false`.  If the value is `true`, then calls to [`imageWithContentsOfURL:options:`](/documentation/CoreImage/CIImage/imageWithContentsOfURL:options:) and [`imageWithData:options:`](/documentation/CoreImage/CIImage/imageWithData:options:) will return the auxiliary image as a half-float monochrome image instead of the primary image, or <doc://com.apple.documentation/documentation/ObjectiveC/nil-227m0> if no auxiliary image exists.

---

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