applyGamma(_:intermediateBuffer:destination:)
Applies a gamma function to an 8-bit-per-channel, 3-channel interleaved pixel buffer.
Declaration
func applyGamma(_ gamma: vImage.Gamma, intermediateBuffer: vImage.PixelBuffer<vImage.InterleavedFx3>? = nil, destination: vImage.PixelBuffer<vImage.Interleaved8x3>)Parameters
- gamma:
An enumeration that specifies either a used-defined or constant gamma.
- intermediateBuffer:
An optional intermediate buffer.
- destination:
The destination pixel buffer.
Discussion
This operation applies gamma to an vImage.Interleaved8x3 buffer by calling the underlying function vImageGamma_Planar8toPlanarF(_:_:_:_:). Therefore, it requires an intermediate vImage.InterleavedFx3 buffer. For the best performance, pass an existing vImage.InterleavedFx3 buffer to intermediateBuffer, alternatively, pass `nil` to specify that the function creates the intermediate buffer.
For example, the following code applies a gamma of 2.0 to a one-pixel pixel buffer:
let buffer = vImage.PixelBuffer<vImage.Interleaved8x3>(
pixelValues: [64, 128, 255],
size: vImage.Size(width: 1,
height: 1))
buffer.applyGamma(.fullPrecision(2),
destination: buffer)
// Prints "[16, 64, 255]" ≅ [255 * 0.25², 255 * 0.5², 255 * 1²].
print(buffer.array)