# transform(_:interpolation:backgroundColor:destination:) Applies a perspective warp to an interleaved 4-channel, 8-bit planar image. ``` func transform(_ transform: vImage_PerpsectiveTransform, interpolation: vImage_PerpsectiveTransform.Interpolation, backgroundColor: Pixel_8888, destination: vImage.PixelBuffer) ``` ## Parameters `transform` The projective-transformation matrix that the function applies. `interpolation` An enumeration that specifies the interpolation mode. `backgroundColor` The background color. `destination` The destination pixel buffer. ## Discussion Use this function to apply a projective-transformation structure to a pixel buffer. Projective transformations warp an image in 3D and allow you to, for example, map a 2D asset to an image of a billboard or television screen. The following code defines source and destination quadrilaterals that specify a projective-transformation structure: ```swift let sourceQuadrilateral = (CGPoint(x: 0, y: 0), // Top-left. CGPoint(x: 1000, y: 0), // Top-right. CGPoint(x: 1000, y: 1000), // Bottom-right. CGPoint(x: 0, y: 1000)) // Bottom-left. let destinationQuadrilateral = (CGPoint(x: 300, y: 375), // Top-left. CGPoint(x: 700, y: 125), // Top-right. CGPoint(x: 700, y: 875), // Bottom-right. CGPoint(x: 300, y: 625)) // Bottom-left. guard let warp = vImage_PerpsectiveTransform( source: sourceQuadrilateral, destination: destinationQuadrilateral) else { return } ``` You pass the `vImage_PerpsectiveTransform` structure to this function to apply the warp to the source pixel buffer and write the result to the destination buffer. ```swift sourceBuffer.transform(warp, interpolation: .linear, backgroundColor: backgroundColor, destination: destinationBuffer) ``` The illustration below shows the original image on the left and the warped image on the right:  > Important: > This function doesn’t work in place — that is, the source and destination buffers need to point to different memory. ## 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)