the Screen Color.
increase in Screen Gain.
The screen gain controls how much of the screen color is removed to make the screen matte. Increasing this value keys more. The figure on the left shows the Status after picking the Screen Color.
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| Status after picking the Screen Color. |
Status showing the increase in Screen Gain. |
You can clearly see that parts of the background are gray where they should be black. When composited, you may see faint pixels from the foreground where you should be seeing pure background. Increasing the screen gain fixes this, as shown in the figure on the right (above), but increasing it too much destroys your good work. Like many keying parameters it’s a balance - not too much, not too little. Increasing the screen gain too much leads to the background showing through the foreground and edge detail can be destroyed. Below, the figure on the right shows this quite well.
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| Screen Gain = 1.05 giving a good Screen Matte. |
Screen Gain = 1.50 giving background show-through and over eroded edges. |
Note the steering wheel is black when it should be white. If you look at the composite, you can see the background showing through here. Also, some of the fine hair detail on the actor, visible in the figure on the left, has been eroded in the figure on the right.
