Keying - Nuke 101: Professional Compositing and Visual Effects - page 304

2. MakesureyouareviewingtheoutputofHueKeyer1.Switchtoviewingthealpha
( FIGURE 7.6 ) .
Figure 7.6. HueKeyer's default alpha channel.
You can see that already there's some kind of alpha in there. This is because, by
default, it's designed to key out a range of greens and cyans. This greenscreen is,
surprisingly, a more yellowish rather than a true green or a cyan green.
3. Switch back to viewing the color channels.
4. Hover your mouse pointer over the greenscreen area and look at HueKeyer1's
graph ( FIGURE 7.7 ) .
Figure 7.7. The yellow line in the graph represents the hue of the color that
the mouse pointer is hovering over.