# vImageBuffer_InitWithCGImage(_:_:_:_:_:) Initializes a vImage buffer with the contents of a Core Graphics image. ``` func vImageBuffer_InitWithCGImage(_ buf: UnsafeMutablePointer, _ format: UnsafeMutablePointer, _ backgroundColor: UnsafePointer!, _ image: CGImage, _ flags: vImage_Flags) -> vImage_Error ``` ## Parameters `buf` The destination vImage buffer. On output, an initialized buffer with all fields populated. `format` A [`vImage_CGImageFormat`](/documentation/Accelerate/vImage_CGImageFormat) structure. Pass an empty structure to specify that the function populates the format with the properties of the Core Graphics image. Pass a populated structure to specify that the function converts the Core Graphics image to the format. `backgroundColor` If the source image contains alpha information and the format doesn’t contain alpha information, this function flattens the source image against this parameter. `image` The source Core Graphics image. `flags` The options to use when performing the operation. Pass [`kvImageNoAllocate`](/documentation/Accelerate/kvImageNoAllocate) if the destination buffer references existing data; otherwise, pass [`kvImageNoFlags`](/documentation/Accelerate/kvImageNoFlags). ## Return Value [`kvImageNoError`](/documentation/Accelerate/kvImageNoError); otherwise, one of the error codes in . ## Discussion The following code shows a passthrough function that accepts a image, populates a vImage buffer from the image, and generates a image from the buffer. In this example, the call to [`vImageBuffer_InitWithCGImage(_:_:_:_:_:)`](/documentation/Accelerate/vImageBuffer_InitWithCGImage(_:_:_:_:_:)) populates the [`vImage_CGImageFormat`](/documentation/Accelerate/vImage_CGImageFormat) and the [`vImage_Buffer`](/documentation/Accelerate/vImage_Buffer) variables with the properties of the source image: ```swift static func passThrough(sourceImage: CGImage) -> CGImage? { var format = vImage_CGImageFormat() var buffer = vImage_Buffer() defer { buffer.free() } vImageBuffer_InitWithCGImage( &buffer, &format, nil, sourceImage, vImage_Flags(kvImageNoFlags)) // Perform image-processing operations on `buffer`. let destinationCGImage = vImageCreateCGImageFromBuffer( &buffer, &format, nil, nil, vImage_Flags(kvImageNoFlags), nil) return destinationCGImage?.takeRetainedValue() } ``` Pass a fully initialized [`vImage_CGImageFormat`](/documentation/Accelerate/vImage_CGImageFormat) to specify that [`vImageBuffer_InitWithCGImage(_:_:_:_:_:)`](/documentation/Accelerate/vImageBuffer_InitWithCGImage(_:_:_:_:_:)) converts the source image to the format that `format` describes. The following example converts the source image to a three-channel, 8-bit-per-channel RGB image: ```swift static func passThrough(sourceImage: CGImage) -> CGImage? { var format = vImage_CGImageFormat( bitsPerComponent: 8, bitsPerPixel: 8 * 3, colorSpace: CGColorSpaceCreateDeviceRGB(), bitmapInfo: CGBitmapInfo(rawValue: CGImageAlphaInfo.none.rawValue), renderingIntent: .defaultIntent)! var buffer = vImage_Buffer() defer { buffer.free() } vImageBuffer_InitWithCGImage( &buffer, &format, nil, sourceImage, vImage_Flags(kvImageNoFlags)) // Perform image-processing operations on RGB888 `buffer`. let destinationCGImage = vImageCreateCGImageFromBuffer( &buffer, &format, nil, nil, vImage_Flags(kvImageNoFlags), nil) return destinationCGImage?.takeRetainedValue() } ``` > Important: If you provide a populated `vImage_CGImageFormat` with properties (such as bit-depth, color space, and channel ordering) that are different from those of the `CGImage` instance, vImage uses [any-to-any conversion](https://developer.apple.com/documentation/accelerate/functions-that-perform-any-to-any-conversion/) as part of the operation. If your app is latency-sensitive, provide either an empty `vImage_CGImageFormat` or a `vImage_CGImageFormat` with properties that match the source image to ensure that the operation avoids the conversion step. --- 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)