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# Transfer Function Extension Constants

Constants that identify transfer function extensions.

## Topics

### Constants

[`let kCMFormatDescriptionTransferFunction_ITU_R_2020: CFString`](/documentation/CoreMedia/kCMFormatDescriptionTransferFunction_ITU_R_2020)

A constant that describes the ITU R 2020 transfer function format.

[`let kCMFormatDescriptionTransferFunction_ITU_R_709_2: CFString`](/documentation/CoreMedia/kCMFormatDescriptionTransferFunction_ITU_R_709_2-swift.var)

A constant that describes the ITU R 709 2 transfer function format.

[`let kCMFormatDescriptionTransferFunction_SMPTE_240M_1995: CFString`](/documentation/CoreMedia/kCMFormatDescriptionTransferFunction_SMPTE_240M_1995-swift.var)

A constant that describes the SMPTE 240M 1995 transfer function format.

[`let kCMFormatDescriptionTransferFunction_SMPTE_ST_428_1: CFString`](/documentation/CoreMedia/kCMFormatDescriptionTransferFunction_SMPTE_ST_428_1)

[`let kCMFormatDescriptionTransferFunction_UseGamma: CFString`](/documentation/CoreMedia/kCMFormatDescriptionTransferFunction_UseGamma-swift.var)

A constant that describes the gamma transfer function format.


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