Contents

multiply(by:divisor:preBias:postBias:destination:)

Multiplies each four channel pixel in an 8-bit-per channel, 4-channel pixel buffer by a four element matrix to produce a single channel result.

Declaration

func multiply(by matrix: (Int, Int, Int, Int), divisor: Int, preBias: (Int, Int, Int, Int), postBias: Int, destination: vImage.PixelBuffer<vImage.Planar8>)

Parameters

  • matrix:

    The 4 x 4 multiplication matrix values in row-major order.

  • divisor:

    A value that the function divides the result by.

  • preBias:

    Values that the function adds to the source before multiplication.

  • postBias:

    A value that the function adds to the result after multiplication.

  • destination:

    The destination pixel buffer.

Discussion

This function applies the following operation to each pixel:

p = (source.0 + preBias.0) * matrix.0 +
    (source.1 + preBias.1) * matrix.1 +
    (source.2 + preBias.2) * matrix.2 +
    (source.3 + preBias.3) * matrix.3
destination = (p + postBias) / divisor

The operation clamps the destination pixel to 0...255.

See Also

Pixel Multiplication