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Luminance Control Macro

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#1 Gringo

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Posted 09 July 2011 - 02:06 PM

This new macro lets you modify the luminance of the image preserving it's saturation.

For example, when you increase the contrast with the BrightnessContrast tool, you also increase the saturation and if you change the gamma, the saturation changes non-linearly in the dark and light areas.

The LuminanceControl macro, however, subtracts the luminance information based on one of three modes: HSV, YUV or HLS (you can choose depending on the situation) and works with it separately from color characteristics.

This can be really important if you have approved colors in the image, but want to change the contrast. It can also help you bring a stylish look to a picture simulating the bleach bypass effect.

Besides, this tool has a wider range for the Low and High controls which lets you use them not only to increase the contrast, but also to decrease it.

http://vfxpedia.com/...rol_v01.setting

#2 Dietmar

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Posted 09 July 2011 - 02:47 PM

Thanks, good work! :mf_prop:

#3 Pilalitos

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Posted 10 July 2011 - 09:32 PM

It's a cool tool but the moment I tried it I thought it could be cooler with a curve control for the luminance.

It does have its uses as it is ofcourse! Thanks!

#4 RockKenny

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Posted 10 July 2011 - 10:17 PM

helpful tool!

#5 Tilt

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Posted 11 July 2011 - 01:04 AM

You can use the regular CCv tool for that, Pilalitos. It can work in HSV space :-)

#6 Gringo

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Posted 11 July 2011 - 03:31 AM

You can use the regular CCv tool for that, Pilalitos. It can work in HSV space :-)

I'd used this approach before I made the macro and it's still actual for more complicated adjustments.

#7 Pilalitos

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Posted 11 July 2011 - 06:34 AM

Ah yes... I was already doing that! I think I had a couple of beers too many last night! ;)

#8 Gringo

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Posted 11 July 2011 - 07:18 AM

Here is the description of the macro with graphs illustrating the effect of different controls:
http://vfxpedia.com/...rol_Description

#9 Garet

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Posted 12 July 2011 - 03:23 AM

Here is the description of the macro with graphs illustrating the effect of different controls:
http://vfxpedia.com/...rol_Description


Good macro as usual. :)

Gregory, there's a lil' legend mistake on your 'Gamma Control' picture. Gamma of 2 darkens the image.

See attached excerpt from "Digital Compositing for Film and Video". Highlights are mine.

Attached Files



#10 bfloch

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Posted 12 July 2011 - 07:45 AM

It depends on the definition.

You are right if you assume that "Gamma" is the exponent as in the technical definition of gamma correction but in his diagramm Gregory refers to the Control Input named "Gamma" which uses the inverse (1/Gamma) as exponent.

So it is right, everything else would be confusing (setting the Gamma control to 2 brightens midtones).

This however could be seen false or at least unclear. But to be honest: I don't mind.

Mathematically, it's exponentiation, color values are raised to the power of the control value. See the graph below.



#11 Gringo

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Posted 12 July 2011 - 11:04 AM

My bad!
Actually, it raises the color values to the power of one divided by the control value.

Thank you for pointing!





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