Luma Key; Linear Key - Blackmagicdesign ATEM Live Installation And Operation Manual

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 made transparent 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 that is used to define regions of the fill signal to be made
transparent. 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, key signals and
the resulting combined image might look like.
Combining a background, fill and key in a linear 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 black parts of
the graphic remain intact because the key signal is used to determine the transparency of the
fill signal. The fill signal is often provided by a graphics system.
Key
A grayscale image that defines the region in the image that will be removed so that the fill
signal can be correctly stacked on top of the background. The key signal is often provided by a
graphics system.
Keying using ATEM Switchers 134