What really is R-YR, R-YB, G-YR, G-YB ? - AVS Forum
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post #1 of 10 Old 03-19-2013, 09:53 AM - Thread Starter
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[Sorry if these are basic questions, but I have not been formally trained in video where this may be taught in Video Systems 101.]


I got back into calibrating my Sony KDS-60A2020 this week while the wife is away on vacation. I got things looking pretty good according to the software using AVSHD and HCFR with an i1-D2. I did grey scale and CMS calibration.

I have questions that have bugged me for years whenever I get the chance to get into a calibration of CMS. What are the definitions for R-YR, R-YB, G-YR, G-YB? As an engineer, I want to know what is really being controlled by these adjustment, not just how to adjust them.

What I have learned from searching the net, including AVS Forums, is to adjust:

Color for Blue Luminance

Tint for Cyan position

R-YR for Red Luminance

G-YR for Green Luminance

R-YB for Magenta position

G-YB for Yellow position

Is R-YB defined as Red Luminance minus Blue Luminance? This works since Magenta position is along the Red-Blue side of the triangle. But then this logic doesn’t work for G-YB. Yellow is along the Red Green side.

Is G-YR a difference between Red and Green?

Is the “-“ not a minus sign? Is "Y" not Luminance? Am I over thinking this?

So what are these controls really adjusting? Or, how are they making the adjustment?
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post #2 of 10 Old 03-20-2013, 12:02 PM
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In what context are you referring to the terms? As labels for controls in the Sony TV? If so, they may mean something to the person who designed the TV and controls and be completely meaningless in actual color science. In general, the controls you adjust in TVs for calibration will be named gain or high or offset or bias or low or cut, usually with just R, G, or B to identify the color they work with. Other controls that may appear in the service menu with undecipherable names could be frightfully convoluted in their use and effect on images and the names of the controls might have little to do with anything in terms of color science. They may not even be color or grayscale calibration controls... they might adjust something related to geometry or some other aspect of the image.

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post #3 of 10 Old 03-20-2013, 01:56 PM - Thread Starter
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I am talking in general terms. The adjustment of a color decoder commonly refers to adjustment of these items. Sometimes written RYR RYB GYR GYB.
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post #4 of 10 Old 03-21-2013, 01:31 AM
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Quote:
Originally Posted by Larry L View Post

The adjustment of a color decoder commonly refers to adjustment of these items.

Right ... those are (most likely) color decoder adjustments. As Doug pointed out, they may or may not correspond actual decoder matrix mathematics.

The only way to know for sure is to ask Sony and they'll probably want to sell you a service manual before they'll even talk to you.
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post #5 of 10 Old 03-21-2013, 07:10 AM
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Quote:
Originally Posted by HDTVChallenged View Post

Right ... those are (most likely) color decoder adjustments. As Doug pointed out, they may or may not correspond actual decoder matrix mathematics.

The only way to know for sure is to ask Sony and they'll probably want to sell you a service manual before they'll even talk to you.

The labels make much more sense if you're using a vectorscope to align the decoder....

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post #6 of 10 Old 03-21-2013, 10:13 AM - Thread Starter
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I would like to forget the brand and labling in a sevice menu and talk generic.

When I read a general CMS calibration article and it states
"Just to be clear, RYR is a red gain control and RYB is a red tint control, primarily affecting the hue of magenta. GYR is a green gain control and GYB is a green tint control primarily affecting the hue of yellow.

From this type of statement I conclude G-YR is adjusting the Lumance of Green by adjusting the gain of the Green amplifier (if we have an analog system) thus pushing the Green gun harder (if we have an CRT). But let's ignor the technology.
Am I correct that GYR controls the Luminance of Green?
Why is it designated G-YR and not just GY or GYG (like RYR ?)

Here is where my first confusion comes in. "GYB is a green tint control primarily affecting the hue of yellow." Is the GYB control moving the xy position of Green. I thought the position of Green (and all primaries) were determined by the hardware characteristics and not adjustable with a CMS. Am I wrong here?

If G-YB is adjusting the ratio of Green/Blue, why is Yellow primarily affected? Why not Cyan?


I imagine these designations are carry-overs from CRT analog TV days, but I am think the concepts are the same today.
I am trying to understand the concept of these controls, not what menu item in a service menu to use.

Thanks for any education here.
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post #7 of 10 Old 03-21-2013, 12:51 PM
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Larry, check out the Wikipedia article on vectorscopes. It does talk a bit about these things and may help you understand a little better. smile.gif

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post #8 of 10 Old 03-22-2013, 10:08 AM
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Quote:
Originally Posted by Rolls-Royce View Post

The labels make much more sense if you're using a vectorscope to align the decoder....

I'll take your word for it. smile.gif I remember seeing some slides about using vectorscopes on "A Video Standard" a/o "Video Essentials" ... but that's about it for my knowledge.

Having said that, I suspect that having all the analog voltages line up correctly doesn't necessarily mean it's going to look right visually. wink.gif
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post #9 of 10 Old 04-05-2013, 10:16 AM - Thread Starter
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OK. Spent some time reading about Vectorscopes, but I still don't see coorelations. I'll keep looking.
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post #10 of 10 Old 04-16-2013, 07:10 PM - Thread Starter
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OK, I have studied about Vectorscopes and now have more questions::

Does RYR adjust the lumanace or the Saturation of Red ? Since the vectoscopre is only reading chroma, I am now thinking it is saturation. Same for GYR.

But I still do not understand these designations. I have not seen G-Y on any scopes yet. And I don't know what the YB inducates.
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