2017

the front clip within the softness range become grey in the matte. The key should have the greatest possible
softness value.
After setting the softness range, you set a range of colours to be keyed out in the key-in clip. This is called
the tolerance range. All pixels in the front clip within the tolerance range become black in the matte. The
tolerance range must not be too large or the edge of the composite will be too hard and the subject in the
front clip will appear to be pasted into the back clip.
About the Different Colour Models
There are four colour models you can use.
HLS
In the HLS Keyer menu, you set the softness and tolerance ranges using the hue, luminance, and saturation
channels.
YUV
In the YUV Keyer menu, you set the softness and tolerance ranges using the luma and chroma signals of
YUV component video.
RGB
In the RGB Keyer menu, you set the softness and tolerance ranges using the red, green, and blue channels.
RGBCMYL
In the RGBCMYL Keyer menu, you set the softness and tolerance ranges using the red, green, blue, cyan,
magenta, yellow, and luminance channels. This colour model provides subpixel resolution.
Selecting a Colour Model Based Component Keyer
To determine which component keyer will give you the best key, try creating a sample matte for each keyer.
To create a sample matte for each keyer:
1 From the Start Mode dropdown list, select one of the following: Reset to RGB, Reset to YUV, Reset to
HLS, Reset to RGBCMYL.
2 Set the View to Key In to view the key-in clip.
3 Double-click the Keyer node in the schematic.
The softness for each model is set automatically to 50, which helps you to quickly gauge the model
that will create the best key for your clip.
4 At frame 1, click the Average Colour pot.
5 Drag the colour picker around the area you want to key out.
698 | Chapter 16 Chroma Keying and Working with Green Screens