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Re: Bad blue screen key - How to get rid of edges without losing detail?

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Darby Edelen
Re: Bad blue screen key - How to get rid of edges without losing detail?
on Jul 22, 2012 at 10:14:46 pm

I'd recommend refreshing yourself on Keylight by giving the documentation a read through. Lots of good information in there. If you google search for "keylight documentation" there should be a PDF result from The Foundry.

You may not need to mask separate sections of this image in order to get a good key. However, you definitely will need to key it at least twice, maybe even three times. With your particular image I saw much better results using a lower Screen Balance value (around 50).

While adjusting these properties I recommend viewing the 'Status' which will show you all fully transparent (black), fully opaque (white), and semi-transparent (gray) areas.

Key once for the edges, preserve softness (but don't add any) and don't worry about "holes" in the foreground subject. This instance of Keylight won't need much adjustment in the Screen Matte section.

Key again for the core of the foreground subjects, this is where you'll use Clip White to make sure the foreground is solid. Since this instance is only for the core of your foreground subject, use Screen Shrink to erode the matte by a pixel or two.

The combination of these two mattes should be good enough for your main subjects. I would usually just lay the edge key layer on top of the core key layer unless more complex work is required.

If you need a better shadow key then you could do that separately as well. Most likely your edge key will preserve the shadows pretty well, so you could simply duplicate that and make some adjustments to preserve more shadow. If you'd like to avoid color spill in the shadows I'd recommend just using Generate > Fill with a black color

Also you'll likely need to use the Despill Bias to remove blue spill from your subjects. I like to click to open the color picker and then use the eye dropper from there to select a foreground color (try a point in skin of your subject) for this operation.

Darby Edelen

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