The IlvBlendFilter Class

The IlvBlendFilter class lets you blend two images A and B using various modes.

The blend modes define the following formulas:

Normal Blend Mode: cr = (1 - qa) * cb + ca

Multiply Blend Mode: cr = (1 - qa) * cb + (1 - qb) * ca + ca * cb

Screen Blend Mode: cr = cb + ca - ca * cb

Darken Blend Mode: cr = Min((1 - qa) * cb + ca, (1 - qb) * ca + cb)

Lighten Blend Mode: cr = Max((1 - qa) * cb + ca, (1 - qb) * ca + cb)

where:

cr	Result color (RGB) - premultiplied
qa	Opacity value at a given pixel for image A
qb	Opacity value at a given pixel for image B
ca	Color (RGB) at a given pixel for image A (premultiplied)
cb	Color (RGB) at a given pixel for image B (premultiplied)

For all blend modes, the resulting opacity qr is computed as follows:

qr = 1 - (1 - qa) * (1 - qb)

Version 6.2.1