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RGB Separation / decoupling and RGB Balance

 
Author Nepomuk
User - Mono 
#1 | Posted: 31 Jan 2013 18:39 
Hi Everyone,

I have learned, that it is desired to use non-decoupling display devices in post.
Please define the terms and elaborate what bad RGB separation means and how it would compromise colour work, even when the RGB Balance is fine, or the other way around.

Thank you.

Author waltervolpatto
User - Mono 
#2 | Posted: 1 Feb 2013 15:05 
the idea is that the tri-stimuli necessary to present a single color/grey should be independent between each other, or in other words, if a correction is needed to tweak the greyscale for your monitor, this correction will be valid and held for the whole colorspace in a very linear fashion...

a single color A(rgb) has to be comprise of three indipendent stimuli (perfect metamerisms) as

A(rgb) = A(R, 0, 0 ) + A(0, G, 0) + A (0, 0, B)

in decoupling display, a stimuli is a blend os poor light source, poor filters that concur to form an image that is pleasing thru additions and subtractions of other color, or in other words you do not get the purity of the stimuli but a blend that approximate it.
In that case a 1D LUT is NOT a good model representation of your calibration but a more dense 3D LUT is necessary.

It is similar to the cross talk you get in the film negative/positive process...

Author Nepomuk
User - Mono 
#3 | Posted: 8 Feb 2013 18:43 
Thanks waltervolpatto,

I am still trying to understand. Could you please define RGB balance as well?

Author Steve

Mod - Scene 
#4 | Posted: 9 Feb 2013 08:21 
RGB Balance is the colour temperature of the grey scale.

It is the same as the crosses in the centre circle of the CIE diagrams.

Steve
Steve Shaw
Mob Boss at Light Illusion

Author Nepomuk
User - Mono 
#5 | Posted: 16 Feb 2013 15:14 
ah! Thanks Steve!

Display Calibration Light Illusion Forums / Display Calibration /
 RGB Separation / decoupling and RGB Balance

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