# Functions that add an alpha channel to three-channel buffers Add a constant alpha value or planar alpha buffer to an RGB image. ## Topics ### Conversion from 8-bit-per-channel, 3-channel interleaved buffers [`func vImageConvert_RGB888toARGB8888(UnsafePointer, UnsafePointer!, Pixel_8, UnsafePointer, Bool, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGB888toARGB8888(_:_:_:_:_:_:)) Combines an 8-bit-per-channel, 3-channel RGB buffer and either an 8-bit alpha buffer or constant alpha value to produce an ARGB result. [`#define vImageConvert_BGR888toBGRA8888(_bgrSrc, _aSrc, _alpha, _bgraDest, _premultiply, _flags)`](/documentation/Accelerate/vImageConvert_BGR888toBGRA8888) Combines an 8-bit-per-channel, 3-channel BGR buffer and either an 8-bit alpha buffer or constant alpha value to produce a BGRA result. [`func vImageConvert_RGB888toBGRA8888(UnsafePointer, UnsafePointer!, Pixel_8, UnsafePointer, Bool, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGB888toBGRA8888(_:_:_:_:_:_:)) Combines an 8-bit-per-channel, 3-channel RGB buffer and either an 8-bit alpha buffer or constant alpha value to produce a BGRA result. [`#define vImageConvert_BGR888toRGBA8888(_bgrSrc, _aSrc, _alpha, _rgbaDest, _premultiply, _flags)`](/documentation/Accelerate/vImageConvert_BGR888toRGBA8888) Combines an 8-bit-per-channel, 3-channel BGR buffer and either an 8-bit alpha buffer or constant alpha value to produce an RGBA result. [`func vImageConvert_RGB888toRGBA8888(UnsafePointer, UnsafePointer!, Pixel_8, UnsafePointer, Bool, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGB888toRGBA8888(_:_:_:_:_:_:)) Combines an 8-bit-per-channel, 3-channel RGB buffer and either an 8-bit alpha buffer or constant alpha value to produce an RGBA result. ### Conversion from unsigned 16-bit-per-channel, 3-channel interleaved buffers [`func vImageConvert_RGB16UToARGB8888(UnsafePointer, UnsafePointer, UnsafePointer, UInt8, UnsafePointer, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGB16UToARGB8888(_:_:_:_:_:_:)) Converts an unsigned 16-bit-per-channel, 3-channel interleaved buffer to an 8-bit-per-channel, 4-channel interleaved buffer using permutation. [`func vImageConvert_RGB16UtoARGB16U(UnsafePointer, UnsafePointer!, Pixel_16U, UnsafePointer, Bool, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGB16UtoARGB16U(_:_:_:_:_:_:)) Combines an unsigned 16-bit-per-channel, 3-channel RGB buffer and either an unsigned 16-bit alpha buffer or constant alpha value to produce an ARGB result. [`func vImageConvert_RGB16UtoBGRA16U(UnsafePointer, UnsafePointer!, Pixel_16U, UnsafePointer, Bool, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGB16UtoBGRA16U(_:_:_:_:_:_:)) Combines an unsigned 16-bit-per-channel, 3-channel RGB buffer and either an unsigned 16-bit alpha buffer or constant alpha value to produce a BGRA result. [`func vImageConvert_RGB16UtoRGBA16U(UnsafePointer, UnsafePointer!, Pixel_16U, UnsafePointer, Bool, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGB16UtoRGBA16U(_:_:_:_:_:_:)) Combines an unsigned 16-bit-per-channel, 3-channel RGB buffer and either an unsigned 16-bit alpha buffer or constant alpha value to produce an RGBA result. ### Conversion from RGB565 16-bit-per-channel, 3-channel interleaved buffers [`func vImageConvert_RGB565toARGB8888(Pixel_8, UnsafePointer, UnsafePointer, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGB565toARGB8888(_:_:_:_:)) Combines an RGB565 3-channel RGB buffer and a constant alpha value to produce an 8-bit-per-channel, 4-channel ARGB buffer. [`func vImageConvert_RGB565toBGRA8888(Pixel_8, UnsafePointer, UnsafePointer, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGB565toBGRA8888(_:_:_:_:)) Combines an RGB565 3-channel RGB buffer and a constant alpha value to produce an 8-bit-per-channel, 4-channel BGRA buffer. [`func vImageConvert_RGB565toRGBA8888(Pixel_8, UnsafePointer, UnsafePointer, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGB565toRGBA8888(_:_:_:_:)) Combines an RGB565 3-channel RGB buffer and a constant alpha value to produce an 8-bit-per-channel, 4-channel RGBA buffer. [`func vImageConvert_RGB565toARGB1555(UnsafePointer, UnsafePointer, Int32, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGB565toARGB1555(_:_:_:_:)) Combines an RGB565 3-channel RGB buffer and a constant alpha value to produce a 4-channel ARGB1555 buffer. [`func vImageConvert_RGB565toRGBA5551(UnsafePointer, UnsafePointer, Int32, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGB565toRGBA5551(_:_:_:_:)) Combines an RGB565 3-channel RGB buffer and a constant alpha value to produce a 4-channel RGBA5551 buffer. ### Conversion from 32-bit-per-channel, 3-channel interleaved buffers [`func vImageConvert_RGBFFFtoARGBFFFF(UnsafePointer, UnsafePointer!, Pixel_F, UnsafePointer, Bool, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGBFFFtoARGBFFFF(_:_:_:_:_:_:)) Combines a floating-point 32-bit-per-channel, 3-channel RGB buffer and either an 32-bit alpha buffer or constant alpha value to produce an ARGB result. [`func vImageConvert_RGBFFFtoBGRAFFFF(UnsafePointer, UnsafePointer!, Pixel_F, UnsafePointer, Bool, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGBFFFtoBGRAFFFF(_:_:_:_:_:_:)) Combines a floating-point 32-bit-per-channel, 3-channel RGB buffer and either an 32-bit alpha buffer or constant alpha value to produce a BGRA result. [`func vImageConvert_RGBFFFtoRGBAFFFF(UnsafePointer, UnsafePointer!, Pixel_F, UnsafePointer, Bool, vImage_Flags) -> vImage_Error`](/documentation/Accelerate/vImageConvert_RGBFFFtoRGBAFFFF(_:_:_:_:_:_:)) Combines a floating-point 32-bit-per-channel, 3-channel RGB buffer and either an 32-bit alpha buffer or constant alpha value to produce an RGBA result. --- 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)