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Keylight problem with the color Yellow

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Danny Winn
Keylight problem with the color Yellow
on Jan 12, 2010 at 5:41:32 am

Ok.

I'm doing a big greenscreen project and the product I'm holding & moving around has a bright yellow logo. Whenever I use Keylight to key out the green it imediately turns the bright yellow into a disgusting kind of orangeish yellow. Can't color correct without ruining all my skin tones and clothing colors.

Does anybody know a way to maintain the exact color of the yellow shot? The product is moving around in my hands so it's not something I can really mask or composite over.

I use the "Screen Matte" technique with the black and white clip but that doesn't help anything.

Please inform, thanks much!


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adam taylor
Re: Keylight problem with the color Yellow
on Jan 12, 2010 at 1:39:11 pm

The way i have found to be most useful is this (apologies if it sounds a bit complex...it does work!)

1. in your comp, duplicate the greenscreen clip and select the upper most of the two tracks.
2. Apply a Hue/Saturation effect.
3. select the colorize option, and then rotate the colour angle until the color values of the greenscreen is sufficiently different to the yellow. it does not need to be green - you can rotate the value until you get as pure a colour as possible (ideally you want pure green, pure blue, pure red, etc. The Keylight effect works best if it has a pure colour value to work with, so if you can avoid blends all the better. Depending on how clean the shot is, you can even raise the saturation a little to improve the colour separations.

4. Apply Keylight (make sure its below the Hue/Saturation effect on the effects palette). Use the eyedropper to select your wildly adjusted greenscreen.
5. switch your display to show the alpha channel and adjust your keylight settings to give a clean edged mask.
6. when happy with the alpha channel, switch back to RGB, and on the lower track (the pristine untouched video) set the trackmatte to alpha.

You may need to do a little adjusting to get it just right and you may also need to do some further masking ... but not often. I use this method to get some really clean keys when the foreground and background have been less than perfect and it works almost all the time.

good luck
Adam

Adam Taylor
Video Editor/Audio Mixer/ Compositor/Motion GFX/Barista
Character Options Ltd
Oldham, UK

http://www.sculptedbliss.co.uk


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Danny Winn
Re: Keylight problem with the color Yellow
on Jan 12, 2010 at 2:15:51 pm

Hey thank a lot Adam,

I will try this. I also got some good results by simply dropping the "Screen Balance" from 50% to about 10%, that helped too.

Thanks again.


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adam taylor
Re: Keylight problem with the color Yellow
on Jan 12, 2010 at 2:19:52 pm

keying is one of those things that sounds easy, but in practice can be anything but.
I came at this solution after trying loads of methods that all seemed lacking. I find this one to be pretty darned good almost all the time.

have fun.

Adam Taylor
Video Editor/Audio Mixer/ Compositor/Motion GFX/Barista
Character Options Ltd
Oldham, UK

http://www.sculptedbliss.co.uk


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Craig Swanson
Re: Keylight problem with the color Yellow
on Apr 7, 2010 at 6:40:50 pm

I used Adam's approach and it worked well. I was keying LA Lakers on a green screen and the yellow jersey was a problem. Why don't the Lakers use a blue screen for their media day shoot??

one note on the hue/saturation effect: I used the green channel to adjust to blue screen. I didn't use colorize.

Thanks Adam!

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adam taylor
Re: Keylight problem with the color Yellow
on Apr 7, 2010 at 6:45:25 pm

glad to hear it worked for you, Craig.
adam

Adam Taylor
Video Editor/Audio Mixer/ Compositor/Motion GFX/Barista
Character Options Ltd
Oldham, UK

http://www.sculptedbliss.co.uk


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