Keying using ATEM Switchers
Chroma Key
Chroma key is commonly used for weather broadcasts, where the meteorologist appears to be
standing in front of a large map. In the studio the presenter is actually standing in front of a blue
or green background. In a chroma key two images are combined using a special technique and
a color from one image is removed, revealing another image behind it. This technique is also
referred to as color keying, color-separation overlay, green screen, or blue screen.
A very common use for chroma keys for backgrounds is computer generated graphics.
It’ssimple to connect an external computer to your ATEM switcher using the HDMI output of the
computer or a video card such as the Blackmagic Design DeckLink or Intensity range and then
play back video clips to your ATEM switcher. If you render a green background on your
animations, you can then key this green to create fast and clean animations of any length.
Keying is easy as the green is computer generated so it’s a very flat color that’s easy to key.
Setting up a Luma/Linear Key on Downstream Keyer 1 using ATEM External
Hardware Panels
ATEM 1 M/E Advanced Panel:
1 Press the ‘DSK 1 tie’ button to enable the downstream keyer on the preview output.
This automatically selects the downstream key menu on the system control LCD,
but you can also press the ‘keyers’ button and press the right arrow to enter the
menu directly.
2 Press the ‘DSK 1’ or ‘DSK 2’ soft button to select which downstream keyer you wish
to use. You don’t have to select the key type as the downstream keyer is always
a luma key.
3 Use the control knobs under the LCD menu to select the fill source and key source.
You can also use the corresponding source select buttons to select the fill and
key source.
4 Once you have chosen the fill source and key source, use the ‘left’ and ‘right’
control buttons to scroll through additional menu screens containing key
parameters such as mask, gain, clip, pre multiplied key settings, and more.
ATEM Broadcast Panel:
1 Press the DSK 1 TIE button to enable the downstream keyer on the preview output.
The M/E 1 system control will dynamically navigate to the DSK 1 menu. You can
manually navigate to the DSK 1 menu by pressing HOME > DSK KEYS > DSK 1.
2 The destination display will say DSK1 fill on the On the ATEM 1 M/E Broadcast
Panel. Select the fill source on the select bus.
3 On the ATEM 2 M/E Broadcast Panel, hold down the DEST SHIFT button and select
the key source on the select bus. On the ATEM 1 M/E Broadcast Panel, hold down
the CUT/FILL button so the destination display says DSK1 cut and select the key
source on the select bus.
4 If performing a linear key, select the same source for both fill and key.
5 Adjust the clip and gain controls to refine the key or press the pre-mult button
for pre-multipled keys. The clip and gain controls are not available for pre-
multipled keys.
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