Adobe After Effects - Manual (Page 496)

Invert
To the top
Glow Based On
Glow Threshold
Glow Radius
Glow Intensity
Composite Original
Glow Colors
Color Looping
Color Loops
Inverts the image after the edges are found. If Invert isn’t selected, edges appear as dark lines on a white background. If selected, edges
appear as bright lines on a black background.
This effect works with 8-bpc color.
Glow effect
The Glow effect finds the brighter parts of an image and then brightens those pixels and surrounding pixels to create a diffuse, glowing aura. The
Glow effect can also simulate overexposure of brightly lit objects. You can base the glow on either the original colors of the image or on its alpha
channel. Glows based on alpha channels produce diffuse brightness only at the edges of the image, between the opaque and transparent regions.
You can also use the Glow effect to create a gradient glow between two colors (A and B colors) and to create multicolor effects with looping.
Rendering the Glow effect at Best quality can change the appearance of the layer. This change is especially true if you use Adobe Photoshop
arbitrary maps to color the glows. Be sure to preview at Best quality before you render the effect.
Glows tend to be brighter and more realistic in 32-bpc projects, because the high dynamic range in a 32-bpc project prevents the color values
of the glow from being clipped. Consider working in 32-bpc color for this reason, even if footage items don’t contain high–dynamic range color
values.
Chris Meyer provides a basic overview of the parameters of the Glow effect in a video tutorial on the Lynda.com website .
This effect works with 8-bpc, 16-bpc, and 32-bpc color.
Original (left), and with effect applied (right)
Determines whether glow is based on color values or transparency values.
Sets a threshold as a percentage brightness to which the glow isn’t applied. A lower percentage produces glow on more of the
image; a higher percentage produces glow on less of the image.
The distance, in pixels, that the glow extends out from the bright areas of the image. Larger values produce diffuse glows; smaller
values produce glows with sharp edges.
The brightness of the glow.
Specifies how to composite the effect results with the layer. On Top places the glow on top of the image, using the blending
method selected for Glow Operation. Behind places the glow behind the image, creating a backlighting result. None separates the glow from the
image.
To reduce the layer to the glow only, choose None for Composite Original and None for Glow Operation. To achieve a glow effect for text that
knocks out (blocks) all layers below it, choose Silhouette Alpha for Glow Operation. These glow effects are more noticeable if the image has a
feathered edge.
The colors of the glow. A & B Colors creates a gradient glow using the colors specified by Color A and Color B controls.
The shape of the gradient curve to use if A & B Colors is selected for Glow Colors.
Creates multicolor ringing in the glow, if you select two or more loops. A single loop cycles through the gradient (or arbitrary map)
specified for Glow Colors.
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