Contents

applyPolynomial(coefficientSegments:boundaries:destination:)

Applies a set of piecewise polynomials to an 8-bit planar buffer and writes the result to a 32-bit planar buffer.

Declaration

func applyPolynomial(coefficientSegments: [[Float]], boundaries: [Float], destination: vImage.PixelBuffer<vImage.PlanarF>)

Parameters

  • coefficientSegments:

    An array that contains the polynomial coefficient array. Each polynomial must be of the same order.

  • boundaries:

    An array of boundary values, in increasing order, that separates adjacent ranges of pixel values. boundaries must contain coefficientSegments.count + 1 elements.

  • destination:

    The destination pixel buffer.

Discussion

The following code shows an example of applying three polynomials to a vImage.Planar8 buffer:

let src = vImage.PixelBuffer<vImage.Planar8>(
    pixelValues: [32, 64, 128, 192, 255],
    size: vImage.Size(width: 5, height: 1))

let dest = vImage.PixelBuffer<vImage.PlanarF>(
    size: src.size)

src.applyPolynomial(coefficientSegments: [ [1, 1, 0],
                                           [0, 1, 0],
                                           [0, 0, 1] ],
                    boundaries: [0, 1/3, 2/3, 1] as [Float],
                    destination: dest)

// Prints:
//  1.0         ≅ 1 * (32 / 255)⁰
//  1.0         ≅ 1 * (64 / 255)⁰

//  0.5019608   ≅ 1 * (128 / 255)¹

//  0.56692046  ≅ 1 * (192 / 255)²
//  1.0         ≅ 1 * (255 / 255)²
print(dest.array)

See Also

Related Documentation

Appying polynomial (8-bit source, 32-bit destination)