Luma Key; Linear Key - Blackmagicdesign ATEM Production Studio 4K Installation And Operation Manual

feature you can record your key mask, or alpha channel, in SD, HD or Ultra HD quality via the
auxiliary output. You can also record your green screen video via the program output at the
same time. Recording both sources is useful if you require detailed chroma key post
production effects.

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 and 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.
Operating your ATEM Switcher 136 136