Stretches the contrast of an ARGB8888 source image.
- iOS 5.0+
- macOS 10.3+
- tvOS 9.0+
- watchOS 2.0+
A pointer to a vImage buffer structure that contains the source image.
A pointer to a vImage buffer data structure. You are responsible for filling out the
rowfields 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 options to use. Set the
kvflag if you plan to perform your own tiling or use multithreading.
Image Do Not Tile
kvflag to copy the alpha channel to the destination image unchanged.
Image Leave Alpha Unchanged
The contrast stretch operation alters the image histogram so that pixel values can be found at both the lowest and highest end of the histogram, with values in between “stretched” in a linear fashion. The contrast stretch operation is done separately for each of the four channels—alpha, red, green, and blue. However, the size and range values are the same for each of the four histograms.
The source and destination buffers must have the same height and the same width.