Luma Key - Blackmagicdesign ATEM Television Studio Installation And Operation Manual

Operating your ATEM Switcher
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Luma Key

A luma key or self key consists of one video source containing the video image that will be stacked on top of
the background. All of the black areas defined by the luminance in the video signal will be removed or cut
out so that the background can be revealed underneath. Since only one image is used to define the areas
to be cut out, a luma key uses the same signal for fill and key. The following images are an example of what
background, luma key signals and the resulting combined image might look like.
Combining a background and fill/key in a luma key
Background - a full screen image, often a camera source.
Fill - the graphic you plan to display on top of your background video. Notice that the final composition
does not retain any black from the graphic because all of the black parts have been cut out of the image.
Linear Key
A linear key consists of two video sources; the fill signal and the key or cut signal. The fill signal contains
a video image which is to be stacked on top of the background, while the key signal contains a grayscale
mask and is used as a blueprint to select regions of the fill signal to be removed or cut out. Since both the
fill and key signals are video inputs, both signals can be in motion while on screen. The following images
are examples of what background, fill and key signals, and the resulting combined image might look like.
Combining a background, fill and key in a linear key