Contents

vImageGamma_Planar8toPlanarF(_:_:_:_:)

Applies a gamma function to an 8-bit planar image to produce a 32-bit planar image.

Declaration

func vImageGamma_Planar8toPlanarF(_ src: UnsafePointer<vImage_Buffer>, _ dest: UnsafePointer<vImage_Buffer>, _ gamma: GammaFunction!, _ flags: vImage_Flags) -> vImage_Error

Parameters

  • src:

    The source vImage buffer.

  • dest:

    A pointer to the destination vImage buffer 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, deallocate the memory to prevent memory leaks.

  • gamma:

    The gamma function object.

  • flags:

    The options to use when performing the operation. If your code implements its own tiling or its own multithreading, pass Kvimagedonottile; otherwise, pass Kvimagenoflags.

Return Value

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

Discussion

This function maps 8-bit values in the range 0...255 to the floating-point range 0.0...1.0.

let source = vImage.PixelBuffer<vImage.Planar8>(
    pixelValues: [  1,
                    3,
                    5,
                   15,
                   17,
                   51 ],
    size: vImage.Size(width: 1, height: 6))

let destination = vImage.PixelBuffer<vImage.PlanarF>(
    size: source.size)

let gamma = vImageCreateGammaFunction(
    1.0,
    Int32(kvImageGamma_UseGammaValue),
    vImage_Flags(kvImageNoFlags))

defer {
    vImageDestroyGammaFunction(gamma)
}

source.withUnsafePointerToVImageBuffer { src in
    destination.withUnsafePointerToVImageBuffer { dest in
        
        _ = vImageGamma_Planar8toPlanarF(
            src,
            dest,
            gamma,
            vImage_Flags(kvImageNoFlags))
        
    }
}

// Prints "[1.0, 3.0, 5.0, 15.0, 17.0, 51.0]".
print(destination.array.map { $0 * 255 })

See Also

Applying a gamma function