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Discussion Starter · #1 ·
Several pro calibrators declared that in order to calibrate 2011 RGBY QUATTRONs correctly the color gamut needed to be set to ''standard''. When RGBY QUATTRONs can be calibrated correctly than why can't they be THX certified? -> Sharp Elite Pro X5FD THX certification required that the yellow sub pixel was turned off.
 

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Quote:
Originally Posted by HDTVChallenged /forum/post/20870221


The short answer is that the yellow sub-pixel is completely unnecessary ... It's a solution in search of a non-existent problem. Plus, from all pro reports, it just makes things worse.

I agree, a display gamut that matches the HD Rec. 709 standard is ideal. Trying to expand it beyond that produces colors not used in reference video content like BD movies and THX video games (or any commercially available video content for that matter). In order for a wider than reference gamut to be useful the video content would need to be created for that wider gamut (which it is not).
 

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I was talking with one of the guys that helped design the Sharp Elites.


What he said is that the yellow pixel does a good job of letting you run a super blue white point while still maintaining some semblance of accuracy in flesh tones.



Rec.709 doesn't require anything but solid additive mixing of color. So once you move the white point back to D65, any need for the yellow pixel is out the window because the yellow color in Rec.709 is simply Red + Green.
 

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Discussion Starter · #5 ·
A Donnymac51 (THX Video Calibrator) post: http://www.avsforum.com/avs-vb/showp...24&postcount=9 - Quote '' I have seen reports from CNET, Kevin Miller and ChadB, they all commented on how well the color gamut calibrated on these set, and their charts backed that up.''


So when color gamut calibrates well on RGBY sets then why needs Y to be shut off in THX mode? Is that because once proper calibrated color gamut is still beyond rec 709?
 

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I doubt yellow needs to be shut off for THX spec or calibrated for industry standards. It either can be calibrated to spec or not. What technology they use to make their displays achieve that spec is not important.


I don't have experience with this particular display so I can't comment if it would be better with it or not to calibrate.
 

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Discussion Starter · #7 ·

Quote:
Originally Posted by BobL; /forum/post/0


I doubt yellow needs to be shut off for THX spec or calibrated for industry standards. It either can be calibrated to spec or not. What technology they use to make their displays achieve that spec is not important.


I don't have experience with this particular display so I can't comment if it would be better with it or not to calibrate.

A quote from Kevin Miller who reviewed the Sharp X5: ''Yellow provides a wider color space and brighter picture, a wider color space is not accurate, this is why THX required the Yellow sub pixel to be shut off.''
 

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Quote:
Originally Posted by sotti /forum/post/20870537


What he said is that the yellow pixel does a good job of letting you run a super blue white point while still maintaining some semblance of accuracy in flesh tones.

Yep ... that's the only semi-legitimate reason for the yellow pixel that I can think of. Of course that's still doing it wrong.
 

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Quote:
Originally Posted by 8mile13 /forum/post/20870861


A quote from Kevin Miller who reviewed the Sharp X5: ''Yellow provides a wider color space and brighter picture, a wider color space is not accurate, this is why THX required the Yellow sub pixel to be shut off.''

This statement may represent the current state of affairs with Quatrron displays, but it's not quite right. There is NO REASON that having yellow pixels MUST create a "wider color space". If the TV is properly designed, you could EASILY have yellow pixels without making the color space larger than the Rec 709 color space standard. You simply change your programming so that when you want yellow, you produce most of the light with the yellow pixels and only use green and red to change the xy coordinates for the shade of yellow you want. You TECHNICALLY should be able to have yellow (or cyan or magenta) pixels without the color space having to be made artificially large/inaccurate.


Unfortunately, in the Quattrons I've looked at, Sharp;s controls don't allow you to completely eliminate oversaturation in yellow. It's not that it can't be done, it's just that Sharp's existing controls don't have enough adjustment range to fix the problem. Putting a Lumagen Radiance video processor in the signal path and calibrating THAT will eliminate the oversaturation in yellow and you can't tell that the TV even has yellow pixels. There are, unfortunately, other problems (primarily low color luminance issues with some other colors) that the Radiance processor (nor the Sharp TV itself) can fix.
 

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Quote:
Originally Posted by 8mile13 /forum/post/20870174


Several pro calibrators declared that in order to calibrate 2011 RGBY QUATTRONs correctly the color gamut needed to be set to ''standard''. When RGBY QUATTRONs can be calibrated correctly than why can't they be THX certified? -> Sharp Elite Pro X5FD THX certification required that the yellow sub pixel was turned off.

The problem is that the best calibration you can get may require Standard mode... that DOES NOT mean that the result in Standard mode is "correct"... it simply means Standard mode minimizes errors. THX apparently determined that even using available controls in the TV, even "Standard" (or any other mode) produced errors considered too large for THX certification. Hence the need to turn off the yellow pixels to avoid the oversaturated yellows that cannot be fixed with controls available in the Quattron TVs. This is a limitation of the CONTROLS. In theory, you could have red, green, blue, yellow, cyan, and magenta pixels in a TV and produce perfect Rec 709/HDTV color space. In fact, an external video processor can eliminate the oversaturated yellows in Quattron TVs - but there are other errors that remain unfixable even with the outboard video processor (primarily color luminance problems). Obviously, THX won't certify a TV that requires an external video processor to make it accurate enough for certification. It will be interesting to see if the color luminance problems have been corrected since the previous generation of Quatrrons.


My guess is that THX told Sharp that there were problems causing the color space to be inaccurate that would have to be fixed before certification would be possible. Sharp was faced with either fixing the controls or turning off the yellow pixels and turning off the yellow pixels for THX mode was easier.


It's a TOTALLY HILARIOUS situation though... think about it... Sharp touts the yellow pixels as a huge advantage over other TVs. Yet to get the TV certified by THX as having relatively accurate images, the yellow pixels had to be turned off. It's essentially equivalent to Sharp admitting that all that yellow pixel stuff they've been touting was just baloney.
 

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When the yellow pixels are turned off, there should be nothing obvious in images that would show up assuming the red, green, and blue pixels work like the RGB pixels in a 3-color panel. But since the remaining RGB pixels are 25% smaller (because the yellow pixels need 25% of the screen area to exist), peak brightness levels could/should be lower for any color that makes use of the yellow pixels. For an LCD panel, this shouldn't be an issue as they typically have PLENTY of luminance to absorb a 25% hit.


Nobody should be sitting so close to a panel that they can see single pixels so the 'holes' will simply disappear within the image.


But this whole thing is just dumb... why pay a premium for a TV with RGBY pixels only to have the yellow pixels turned off in the most accurate mode the TV offers? It would be like paying extra for a car with 6 wheels only to have it work better when only 4 wheels were being used.
 

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Quote:
Originally Posted by Doug Blackburn /forum/post/20873752


This statement may represent the current state of affairs with Quatrron displays, but it's not quite right. There is NO REASON that having yellow pixels MUST create a "wider color space". If the TV is properly designed, you could EASILY have yellow pixels without making the color space larger than the Rec 709 color space standard. You simply change your programming so that when you want yellow, you produce most of the light with the yellow pixels and only use green and red to change the xy coordinates for the shade of yellow you want. You TECHNICALLY should be able to have yellow (or cyan or magenta) pixels without the color space having to be made artificially large/inaccurate.

It's certainly possible to have accurate colour with an RGBY display, but you need a great deal of precision (gradation) to do it without a significant loss of image quality, and with every other display out there being RGB, it will need custom hardware/software to do it. This is all rather expensive, and even when Sharp were making RGB displays, they had serious problems with gradation.

Quote:
Originally Posted by Doug Blackburn /forum/post/20898027


Nobody should be sitting so close to a panel that they can see single pixels so the 'holes' will simply disappear within the image.

THX recommends a 40° field of view and I personally prefer a 45° FOV. (EBU's 2x screen height recommendation)


I am currently using a Sony HX909 which uses Sharp's RGB UV2A panel. The way the pixels are addressed on these panels, sometimes the upper/lower half of a subpixel is turned off.


This is obvious even when sitting much further from the screen. Losing an entire column of sub pixels will be even more visible. (and I bet they still do the same upper/lower half thing this year too)

Quote:
Originally Posted by Doug Blackburn /forum/post/20898027


But this whole thing is just dumb... why pay a premium for a TV with RGBY pixels only to have the yellow pixels turned off in the most accurate mode the TV offers? It would be like paying extra for a car with 6 wheels only to have it work better when only 4 wheels were being used.

Better efficiency and stronger colors for people that don't care about accuracy as much. In theory, if they had got the CMS right, you would have good color accuracy with better energy efficiency. Shame they couldn't do it, but I'm not surprised at all.
 

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Discussion Starter · #15 ·

Quote:
Originally Posted by doug blackburn /forum/post/20898027


when the yellow pixels are turned off, there should be nothing obvious in images that would show up assuming the red, green, and blue pixels work like the rgb pixels in a 3-color panel. But since the remaining rgb pixels are 25% smaller (because the yellow pixels need 25% of the screen area to exist), peak brightness levels could/should be lower for any color that makes use of the yellow pixels. For an lcd panel, this shouldn't be an issue as they typically have plenty of luminance to absorb a 25% hit.


Nobody should be sitting so close to a panel that they can see single pixels so the 'holes' will simply disappear within the image.


But this whole thing is just dumb... Why pay a premium for a tv with rgby pixels only to have the yellow pixels turned off in the most accurate mode the tv offers? It would be like paying extra for a car with 6 wheels only to have it work better when only 4 wheels were being used.

thanks!
 

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Discussion Starter · #16 ·
This whole thread is based upon Kevin Millers statements regarding the yellow sub pixel in a pre-production Sharp Elite Pro TVs THX mode.

Kevin Miller:

'The yellow sub pixel creates very saturated intense colors especially golds and yellows as you can imagine. The reason they are doing it is to appeal to the masses with overly saturated colors. its a good marketing scheme, but for those of us interested in accuracy it has no place.'


'THX required the Yellow Sub Pixel to be shut off. Yes its provides a wider color space and a brighter picture. However, a wider color space is not accurate. Until the standard is changed from Rec 709 to something else, and program material is produced in that new standard than anything outside of it will not reproduce film based material accurately on Blu-ray or broadcast.'


'I got a stunning performance out of it calibrated in the THX mode without the yellow pixel'.


In the Sharp Elite Pro the yellow sub pixel is not turned off in THX mode



Here are some buzzard767 posts that will confirm this:

http://www.avsforum.com/avs-vb/showp...&postcount=513

http://www.avsforum.com/avs-vb/showp...&postcount=523



Seems to me that only in the pre-production Sharp Elite Pro TV that Kevin Miller calibrated the yellow sub pixel was turned off in THX mode.
 

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The picture you linked to on 8-28 PROVES why they can't shut off the yellow. Again, you'd lose nearly 1/4 of the brightness. But that is hardly the biggest problem.


You'd get a massive, hideous vertical screen-door effect, and lose nearly 1/4 of the pixel fill. The TV would look terrible at some reasonably common viewing distances.
 

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Quote:
Originally Posted by Doug Blackburn /forum/post/20873786


My guess is that THX told Sharp that there were problems causing the color space to be inaccurate that would have to be fixed before certification would be possible. Sharp was faced with either fixing the controls or turning off the yellow pixels and turning off the yellow pixels for THX mode was easier.

Doug, as an owner of a 60" Elite, I can attest to the fact the yellow sub-pixels are indeed 'on' even during THX mode. So there seems to be some gap in what Sharp said originally (pre-production) and what Sharp has told several people post-production. Either way, the magnifying glass doesn't lie, the yellows are lit in THX mode as well as other modes.


Now I'm not sure what CMS controls existed in prior non-Elite Sharps, but the Elites have a pretty extensive menu of calibration controls. In addition to CMS hue, there is also CMS saturation & value. So I suspect, yellow pixels on or off, it should be doable to get a conforming to REC709. Interestingly, I've found by playing with the CMS controls, I get better accuracy in the non-THX movie mode.


Perhaps a calibrator would get a very different result.
 

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Greetings


IT's on. They are just required to get the math right and I guess they do.


regards
 

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Quote:
Originally Posted by Ken Ross /forum/post/20971995


Doug, as an owner of a 60" Elite, I can attest to the fact the yellow sub-pixels are indeed 'on' even during THX mode. So there seems to be some gap in what Sharp said originally (pre-production) and what Sharp has told several people post-production. Either way, the magnifying glass doesn't lie, the yellows are lit in THX mode as well as other modes.


Now I'm not sure what CMS controls existed in prior non-Elite Sharps, but the Elites have a pretty extensive menu of calibration controls. In addition to CMS hue, there is also CMS saturation & value. So I suspect, yellow pixels on or off, it should be doable to get a conforming to REC709. Interestingly, I've found by playing with the CMS controls, I get better accuracy in the non-THX movie mode.


Perhaps a calibrator would get a very different result.

Three things matter... what controls exist AND whether those controls work right AND whether the controls can fix problems.


Last years' Quattrons had the same controls but they could NOT fix all the problems - there were residual color errors (yellow remained oversaturated even when the entire adjustment range of the controls was used to reduce saturation of yellow), residual color luminance errors (fairly large ones for several colors), and there was what was presumably a grayscale problem at about 95% white that lead to some values of Caucasian fleshtones turning gray. Presuming Sharp started the process with the same controls working the same ways, they would have had to be able to fix all those problems before getting the images good enough for THX certification. And the point was someone here said the yellow pixels were turned off - that now turns out to be true. It would have been a real debacle for Sharp if they'd have to have turned off the yellow pixels. Apparently they decided to attack the functionality of the controls to get the adjustment range needed to fix all the problems that would have prevented THX certification.
 
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