# premultipliedAlphaBlend(_:topLayer:destination:) Performs alpha compositing of two 4-channel interleaved RGBA 8-bit pixel buffers using the specified blend mode to produce a premultiplied result. ``` func premultipliedAlphaBlend(_ blendMode: vImage.BlendMode, topLayer: vImage.PixelBuffer, destination: vImage.PixelBuffer) ``` ## Parameters `blendMode` The blend mode. `topLayer` The blend top layer. `destination` The destination pixel buffer. ## Discussion This function treats `self` as the bottom layer and both pixel buffers must have alpha as their last channel. ## See Also --- 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)