---
title: hdrGainMapImage
framework: coreimage
role: symbol
role_heading: Type Property
path: coreimage/ciimagerepresentationoption/hdrgainmapimage
---

# hdrGainMapImage

An optional key and value to save a gain map channel to a JPEG or HEIF.

## Declaration

```swift
static let hdrGainMapImage: CIImageRepresentationOption
```

## Discussion

Discussion The value for this key needs to be a monochrome CIImage instance. If the hdrGainMapAsRGB option it true, then it needs to be an RGB CIImage instance. The /CIImage/properties should contain metadata information equivalent to what is returned when initializing an image using auxiliaryHDRGainMap.