# vImageConvert_RGBA5551toRGBA8888(_:_:_:) Converts an RGB5651 4-channel interleaved buffer to an 8-bit-per-channel, 4-channel interleaved buffer. ``` func vImageConvert_RGBA5551toRGBA8888(_ src: UnsafePointer, _ dest: UnsafePointer, _ flags: vImage_Flags) -> vImage_Error ``` ## Parameters `src` The source vImage buffer. `dest` A pointer to the destination vImage buffer structure. You’re responsible for filling out the [`height`](/documentation/Accelerate/vImage_Buffer/height), [`width`](/documentation/Accelerate/vImage_Buffer/width), and [`rowBytes`](/documentation/Accelerate/vImage_Buffer/rowBytes) fields of this structure, and for allocating a data buffer of the appropriate size. On return, the data buffer this structure points to contains the destination image data. When you no longer need the data buffer, deallocate the memory to prevent memory leaks. `flags` The options to use when performing the operation. If your code implements its own tiling or its own multithreading, pass [`kvImageDoNotTile`](/documentation/Accelerate/kvImageDoNotTile); otherwise, pass [`kvImageNoFlags`](/documentation/Accelerate/kvImageNoFlags). ## Return Value [`kvImageNoError`](/documentation/Accelerate/kvImageNoError); otherwise, one of the error codes in . ## Discussion The RGBA5551 format has 16-bit pixels with 1 bit for alpha and 5 bits each for red, green, and blue. The function uses the following calculation to perform the conversion: ```objc Pixel8 alpha = 1bitAlphaChannel * 255 Pixel8 red = (5bitRedChannel * 255 + 15) / 31 Pixel8 green = (5bitGreenChannel * 255 + 15) / 31 Pixel8 blue = (5bitBlueChannel * 255 + 15) / 31 ``` --- 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)