Adobe 65021048 User Guide - Page 342

ADOBE PREMIERE PRO CS3 336 User Guide A B C D Chroma Key effect A. Original image B. Blue color keyed out C. Image on second track D. Final composite image See also "About Chroma Key" on page 370 Color Key effect The Color Key effect keys out all image pixels that are similar to a specified key color. This effect modifies only the alpha channel of a clip. Nonstandard blue screen (left) and background (center) are combined with Color Key (right). When you key out a color value in a clip, that color or range of colors becomes transparent for the entire clip. Control the range of transparent colors by adjusting the tolerance level. You can also feather the edges of the transparent area to create a smooth transition between the transparent and opaque areas. See also "Make a color transparent with Color Key" on page 370 Difference Matte effect The Difference Matte effect creates transparency by comparing a source clip with a difference clip, and then keying out pixels in the source image that match both the position and color in the difference image. Typically, it's used to key out a static background behind a moving object, which is then placed on a different background. Often the difference clip is simply a frame of background footage (before the moving object has entered the scene). For this reason, the Difference Matte Key effect is best used for scenes that have been shot with a stationary camera and an unmoving background. For more information on using the Difference Matte, watch the online training video on the Total Training website. A B C D Difference Matte effect A. Original image B. Background image C. Image on second track D. Final composite image April 1, 2008