Blending Modes

From Mographwiki.net

Blend Modes describe how layers in a Comp are mixed together. They were once called Transfer Modes.

Screen

Screen is an additive compositing mode that looks somewhat like a double exposure. It is achieved by inverting the two layers, multiplying them, and then inverting the result:

1-((1-a)*(1-b))

Black is a transparent color on a layer set to Screen mode. White and white screen together to create white.

The inverse of Screen is Multiply.

Multiply

Multiply simply multiplies the pixel values of the top layer with the bottom layer. White is transparent, since 1.0x = x. Multiply is a great simulation of the darkening effect a filter or other translucent object creates — i.e. multiplying two images together looks a lot like overlapping two transparencies on a light table.

The inverse of Multiply is Screen.

Hard Light

Hard Light is a blend mode where 50% gray is transparent. Where the top layer is brighter than 50% gray, it is screened, and where it is darker, it is multiplied. The net effect of this is that the shadow and highlights of the top layer seem to "burn" onto the bottom. Hard Light is great for combining bump or displacement map layers, which tend to center around middle gray. The opposite of Hard Light, in spirit anyway, is Overlay.