# vImageCreateGammaFunction(_:_:_:) Returns a gamma function object. ``` func vImageCreateGammaFunction(_ gamma: Float, _ gamma_type: Int32, _ flags: vImage_Flags) -> GammaFunction! ``` ## Parameters `gamma` The gamma value when `gamma_type` is [`kvImageGamma_UseGammaValue`](/documentation/Accelerate/kvImageGamma_UseGammaValue) or [`kvImageGamma_UseGammaValue_half_precision`](/documentation/Accelerate/kvImageGamma_UseGammaValue_half_precision). `gamma_type` A constant that specifies the gamma type. See . `flags` Reserved for future use. Pass [`kvImageNoFlags`](/documentation/Accelerate/kvImageNoFlags). ## Return Value A gamma function object that encapsulates a gamma value, a gamma function type, and option flags. ## Discussion Use this function to create a gamma function object that you pass to [`vImageGamma_Planar8toPlanarF(_:_:_:_:)`](/documentation/Accelerate/vImageGamma_Planar8toPlanarF(_:_:_:_:)), [`vImageGamma_PlanarFtoPlanar8(_:_:_:_:)`](/documentation/Accelerate/vImageGamma_PlanarFtoPlanar8(_:_:_:_:)), or [`vImageGamma_PlanarF(_:_:_:_:)`](/documentation/Accelerate/vImageGamma_PlanarF(_:_:_:_:)). The vImage library provides a user-defined half-precision gamma type and constant half-precision gamma types, such as [`kvImageGamma_sRGB_forward_half_precision`](/documentation/Accelerate/kvImageGamma_sRGB_forward_half_precision). Use a half-precision gamma type when creating a gamma function for image data that’s intended for conversion to 8-bit. The half-precision gamma types work with floating-point values in the range `0...1` and provide a precision of ±1 / 4,096. The gamma correction functions that use a [`GammaFunction`](/documentation/Accelerate/GammaFunction) object are symmetric around zero. That is, they treat negative values as if they’re positive, and restore the sign after applying the exponent. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)