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| You basically learn from difficult keys, sometimes there's no easy solution. One thing to look at is pre-processing your footage before keying. In many cases noise reduction or grain removal can have dramatic results on your output. The standard AE grain removal plugin can be bit coarse when it comes to temporal smoothing, but it's better than nothing. Grain / noise management is really important for good clean keys. Apart from grain removal, for keylight you can try doing a hue shift to increase the difference between the green channel and the red and blue channels. This will give you a different result, but not necessarily a better result. Keylight is a difference keyer - it looks at the difference between the green channel and the red / blue channels. Greenscreens are very rarely a purely 'digital' green - most greens have a lot of red in them and are actually quite yellow. Apply the hue / sat filter, and then apply the levels filter so you get a histogram. You should be able to see three clear peaks in the histogram for red / green / blue. Adjusting the hue will move these peaks, and shifting the hue by a few degrees will move the red peak further away from the green, and start moving the blue closer (or vice versa). Find a value that puts the most difference between the green and the red/blue channels. In SOME cases this will give you a better result with fine edge detail such as hair. I've done a few side-by-side comparisons with hue shifted green screens and they've been better about half the time. If you are hue-shifting by a large amount you'll probably want to use the keyed layer as an alpha matte for the original source. -Chris On 20/04/2013, at 2:10 PM, Jonathan <sureal@charter.net> wrote:
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