User Guide

CHAPTER 7
264
Working with Masks and Transparency
Color Creates resulting colors with the luminance of the underlying colors and the hue
and saturation of the layer colors. This preserves the gray levels in the image.
Luminosity Creates resulting colors with the hue and saturation of the underlying colors
and the luminance of the layer colors. This option is the inverse of the Color option.
Alpha Add Composites layers normally, but adds complementary alpha channels together
to create a seamless area of transparency. Useful for removing visible edges from two alpha
channels that are inverted relative to each other, or from the alpha channel edges of two
touching layers that are being animated.
Luminescent Premul Prevents clipping of color values that exceed the alpha channel value
after compositing by adding them to the composition. Useful for compositing rendered
lens or light effects (such as lens flare) from footage with premultiplied alpha channels.
May also improve results when compositing footage from other manufacturers’ matting
software. When applying this mode, you may get the best results by changing After Effects’
interpretation of the premultiplied-alpha source footage to straight alpha (see “Inter-
preting alpha channels as straight or premultiplied” on page 72).
To apply a layer mode:
1 If the Mode menu is not visible in the Timeline window, click the Switches/Mode
button at the bottom of the Timeline window.
2 From the layer’s Mode pop-up menu, choose a mode.
Using stencil and silhouette layer modes
The stencil and silhouette layer modes use either a layer’s alpha channel or its luminance
(luma) values to affect the alpha channel of all layers beneath the layer. This differs from
the track matte, which affects only one layer.
Stencil mode Cuts through all layers, so you can show multiple layers through the frame
of the stencil layer’s alpha channel.
Silhouette mode Blocks out all layers below it, so you can cut a hole through several layers
at once.
Note: The stencil and silhouette layer modes affect all layers below the layer to which they are
applied. To keep the silhouette and stencil layer modes from cutting through or blocking all
layers underneath, nest the layer in a composition. For more information on nesting, see
“Creating animations by nesting compositions” on page 345.
UG.book Page 264 Wednesday, February 21, 2001 12:05 PM