Function

vImageMin_ARGBFFFF(_:_:_:_:_:_:_:_:)

Minimizes a region of interest within an ARGBFFFF source image using an M x N kernel.

Declaration

func vImageMin_ARGBFFFF(_ src: UnsafePointer<vImage_Buffer>, _ dest: UnsafePointer<vImage_Buffer>, _ tempBuffer: UnsafeMutableRawPointer!, _ srcOffsetToROI_X: vImagePixelCount, _ srcOffsetToROI_Y: vImagePixelCount, _ kernel_height: vImagePixelCount, _ kernel_width: vImagePixelCount, _ flags: vImage_Flags) -> vImage_Error

Parameters

src

A pointer to a vImage buffer structure that contains data for the source image.

dest

A pointer to a vImage buffer data structure. You are 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 pointed to by this structure contains the destination image data. When you no longer need the data buffer, you must deallocate the memory.

The size (number of rows and number of columns) of the destination buffer also specifies the size of the region of interest in the source buffer.

tempBuffer

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 are responsible for deallocating it when you is no longer need it.

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

srcOffsetToROI_X

The horizontal offset, in pixels, to the upper-left pixel of the region of interest within the source image.

srcOffsetToROI_Y

The vertical offset, in pixels, to the upper-left pixel of the region of interest within the source image.

kernel_height

The height of the kernel in pixels. This value must be odd.

kernel_width

The width of the kernel in pixels. This value must be odd.

flags

The options to use when performing the morphological operation. Set the kvImageDoNotTile flag if you plan to perform your own tiling or use multithreading. Set the kvImageLeaveAlphaUnchanged flag to specify that the alpha channel should be copied to the destination image unchanged.

Return Value

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

Discussion

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 in 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, do not pass the kvImageGetTempBufferSize flag.

The morphological operation Min is a special case of the erosion operation. In the Min operation, all the elements of the kernel have the same value. The actual value does not matter; only the size of the kernel is significant. vImage optimizes this special case, so the Min function is considerably faster than the Erode function called with a uniform kernel.