# vImage.CompositeMode Constants that specify whether the format of layers is premultiplied or nonpremultiplied. ``` enum CompositeMode ``` ## Topics ### Enumeration Cases [`case nonpremultiplied`](/documentation/Accelerate/vImage/CompositeMode/nonpremultiplied) Composite two non-premultiplied images, to produce a non-premultiplied result. [`case nonpremultipliedToPremultiplied`](/documentation/Accelerate/vImage/CompositeMode/nonpremultipliedToPremultiplied) Blends a nonpremultiplied top image into a premultiplied bottom image and returns a premultiplied result. [`case premultiplied`](/documentation/Accelerate/vImage/CompositeMode/premultiplied) Blends two premultiplied images to produce a premultiplied result. [`case premultipliedWithConstantAlpha(ComponentType)`](/documentation/Accelerate/vImage/CompositeMode/premultipliedWithConstantAlpha(_:)) Performs premultiplied alpha compositing of two images, using a single alpha value for the entire image. ## 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)