# vImageConvert_RGBA8888toRGB565(_:_:_:) Removes the alpha channel from an 8-bit-per-channel RGBA buffer to produce an RGB565 result. ``` func vImageConvert_RGBA8888toRGB565(_ 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 function uses the following calculation to perform the conversion: ```objc uint32_t red = (8bitRedChannel * (31*2) + 255) / (255*2) uint32_t green = (8bitGreenChannel * 63 + 127) / 255 uint32_t blue = (8bitBlueChannel * 31 + 127) / 255 uint16_t RGB565pixel = (red << 11) | (green << 5) | blue ``` --- 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)