Scales a CbCr16U source image to fit a destination buffer.


func vImageScale_CbCr16U(_ src: UnsafePointer<vImage_Buffer>, _ dest: UnsafePointer<vImage_Buffer>, _ tempBuffer: UnsafeMutableRawPointer!, _ flags: vImage_Flags) -> vImage_Error



A pointer to a vImage buffer structure that contains the source image whose data you want to scale.


A pointer to a vImage buffer data structure. You're responsible for filling out the height, width, and 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, you must deallocate the memory.


A pointer to a temporary buffer. If you pass NULL, the function allocates the buffer, then deallocates it before returning. Alternatively, you can allocate the buffer yourself, in which case you're responsible for deallocating it when you no longer need it.

If you want to allocate the buffer yourself, see Allocating Temporary Buffer Memory for information on how to determine the minimum size that you must allocate.


The options to use when applying the scaling.

To specify how vImage handles pixel locations beyond the edge of the source image, you must set exactly one of the following flags: kvImageBackgroundColorFill or kvImageEdgeExtend.

If you want vImage to use a higher quality, but slower resampling filter, set the kvImageHighQualityResampling flag.

If you plan to perform your own tiling or use multithreading, set the kvImageDoNotTile flag.

This function ignores the kvImageLeaveAlphaUnchanged flag.

Return Value

kvImageNoError; otherwise, one of the error codes described in Data Types and Constants.


The relative size of the source image and the destination buffer determine the scaling factors, which may be different in the X and Y directions.

Allocating Temporary Buffer Memory

If you want to allocate the memory for the tempBuffer parameter yourself, call this function twice, as follows:

  1. To determine the minimum size for the temporary buffer, the first time you call this function, pass the kvImageGetTempBufferSize flag. Pass the same values for all other parameters that you intend to use for the second call. The function returns the required minimum size, which should be a positive value. (A negative returned value indicates an error.) The kvImageGetTempBufferSize flag prevents the function from performing any processing other than to determine the minimum buffer size.

  2. After you allocate enough space for a buffer of the returned size, call the function a second time, passing a valid pointer in the tempBuffer parameter. This time, don't pass the kvImageGetTempBufferSize flag.