# CGGetDisplayTransferByTable(_:_:_:_:_:_:) Gets the values in the RGB gamma tables for a display. ``` func CGGetDisplayTransferByTable(_ display: CGDirectDisplayID, _ capacity: UInt32, _ redTable: UnsafeMutablePointer?, _ greenTable: UnsafeMutablePointer?, _ blueTable: UnsafeMutablePointer?, _ sampleCount: UnsafeMutablePointer?) -> CGError ``` ## Parameters `display` The identifier of the display to be accessed. `capacity` The number of entries each table can hold. `redTable` A pointer to an array of type `CGGammaValue` with size `capacity`. On return, the array contains the values of the red channel in the display’s gamma table. `greenTable` A pointer to an array of type `CGGammaValue` with size `capacity`. On return, the array contains the values of the green channel in the display’s gamma table. `blueTable` A pointer to an array of type `CGGammaValue` with size `capacity`. On return, the array contains the values of the blue channel in the display’s gamma table. `sampleCount` The number of samples actually copied into each array. ## Return Value A result code. See `Core Graphics Data Types and Constants`. ## Discussion --- 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)