The IlvColorMatrixFilter Class

The IlvColorMatrixFilter class lets you apply a matrix transformation on the RGBA components of an input image.

The matrix is given as 5*4 row major order coefficients.

| R' | | a00 a01 a02 a03 a04 | | R |

| G' | | a10 a11 a12 a13 a14 | | G |

| B' | = | a20 a21 a22 a23 a24 | * | B |

| A' | | a30 a31 a32 a33 a34 | | A |

| 1 | | 0 0 0 0 1 | | 1 |

This class has three subclasses with specific coefficients.

The IlvSaturationFilter Class

IlvSaturationFilter computes the transformation matrix from the formula:

| R' | |0.213+0.787s 0.715-0.715s 0.072-0.072s 0 0 | | R |

| G' | |0.213-0.213s 0.715+0.285s 0.072-0.072s 0 0 | | G |

| B' | = |0.213-0.213s 0.715-0.715s 0.072+0.928s 0 0 | * | B |

| A' | | 0 0 0 1 0 | | A |

| 1 | | 0 0 0 0 1 | | 1 |

where s is the saturation factor.

The IlvHueRotateFilter Class

IlvHueRotateFilter computes the transformation matrix from the formula:

| R' | | a00 a01 a02 0 0 | | R |

| G' | | a10 a11 a12 0 0 | | G |

| B' | = | a20 a21 a22 0 0 | * | B |

| A' | | 0 0 0 1 0 | | A |

| 1 | | 0 0 0 0 1 | | 1 |

where the terms a00, a01, and so on, are calculated as follows:

| a01 a01 a02 | [+0.213 +0.715 +0.072]

| a10 a11 a12 | = [+0.213 +0.715 +0.072] +

| a20 a21 a22 | [+0.213 +0.715 +0.072]

[+0.787 -0.715 -0.072]

cos(hueRotate value) * [-0.212 +0.285 -0.072] +

[-0.213 -0.715 +0.928]

sin(hueRotate value) * [+0.143 +0.140 -0.283]

[-0.787 +0.715 +0.072]

where value is the angle of rotation for the hue.

Thus, the upper-left term of the hue matrix turns out to be:

.213 + cos(hueRotate value)*.787 - sin(hueRotate value)*.213

The IlvLuminanceToAlphaFilter Class

IlvLuminanceToAlphaFilter computes the transformation matrix from the formula:

| R' | | 0 0 0 0 0 | | R |

| G' | | 0 0 0 0 0 | | G |

| B' | = | 0 0 0 0 0 | * | B |

| A' | | 0.2125 0.7154 0.0721 0 0 | | A |

| 1 | | 0 0 0 0 1 | | 1 |

This filter converts color images to grayscale images.

Version 6.0