Apple Final Cut Pro 6 - Manual (Page 1186)

Chapter 19 Compositing and Layering 401
II
Overlay
Whites and blacks in the foreground image become translucent and interact with the
color values of the background image, causing intensified contrast. Whites and blacks
in the background image, on the other hand, replace overlapping areas in the
foreground image.
Overlapping midrange values are mixed together differently depending on the
brightness of the background color values. Lighter background midrange values are
mixed by screening. Darker background midrange values, on the other hand, are mixed
together by multiplying.
The visible result is that darker color values in the background image intensify
overlapping areas in the foreground image, while lighter color values in the
background image wash out overlapping areas in the foreground image.
The order of two clips affected by the Overlay composite mode is important.
Suggested uses: The Overlay composite mode is particularly useful for combining areas
of vivid color in two images.
Boxes clip on top Monkey clip on top