---
title: kCGImageDestinationPreserveGainMap
framework: imageio
role: symbol
role_heading: Global Variable
path: imageio/kcgimagedestinationpreservegainmap
---

# kCGImageDestinationPreserveGainMap

A Boolean value that indicates whether to include a HEIF-embedded gain map in the image data.

## Declaration

```swift
let kCGImageDestinationPreserveGainMap: CFString
```

## Discussion

Discussion The value of this key must be a CFBoolean value. The default value is kCFBooleanFalse. If you scale the destination image using the kCGImageDestinationImageMaxPixelSize key, the destination also scales the gain map.

## See Also

### Configuring the Image Behaviors

- [kCGImageDestinationLossyCompressionQuality](imageio/kcgimagedestinationlossycompressionquality.md)
- [kCGImageDestinationBackgroundColor](imageio/kcgimagedestinationbackgroundcolor.md)
- [kCGImageDestinationDateTime](imageio/kcgimagedestinationdatetime.md)
- [kCGImageDestinationEmbedThumbnail](imageio/kcgimagedestinationembedthumbnail.md)
- [kCGImageDestinationImageMaxPixelSize](imageio/kcgimagedestinationimagemaxpixelsize.md)
- [kCGImageDestinationMetadata](imageio/kcgimagedestinationmetadata.md)
- [kCGImageDestinationMergeMetadata](imageio/kcgimagedestinationmergemetadata.md)
- [kCGImageDestinationOptimizeColorForSharing](imageio/kcgimagedestinationoptimizecolorforsharing.md)
- [kCGImageDestinationOrientation](imageio/kcgimagedestinationorientation.md)
- [kCGImageMetadataShouldExcludeGPS](imageio/kcgimagemetadatashouldexcludegps.md)
- [kCGImageMetadataShouldExcludeXMP](imageio/kcgimagemetadatashouldexcludexmp.md)