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Gamma and Curves


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#1 Aaron Solomon

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Posted 04 August 2010 - 06:01 PM

Ok so I know this post isn't really HD specific but no one commented anywhere else so here we go:

Hi all,

I hear about gamma and alpha channels often, could someone explain them to me? Also could someone help me with color curves?

Thanks,
Aaron
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#2 Brian Drysdale

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Posted 05 August 2010 - 02:29 AM

Gamma: http://www.dpreview....ng/Gamma_01.htm

Basically each part of the imaging process has a different gamma, but when you add them up up you want to have unity. Considering gamma as a straight line is easier to understand initially and older broadcast engineers thought having this was an advantage over film. However, by having a curve at either end you can retain more information eg your video image retains more white detail before it's clipped.

Alpha channel: http://www.icongalor...l-explained.htm

Colour curves: http://www.ledet.com...1-Defanging.pdf
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#3 Aaron Solomon

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Posted 05 August 2010 - 06:11 AM

Thanks!

Aaron
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