Are current 4K displays ready for "Real" UHD & Rec. 2020? - AVS Forum
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post #1 of 47 Old 08-08-2013, 02:43 PM - Thread Starter
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I have a few questions about the current displays coming out with 4K resolution:

  • AFAIK the UHD spec mandates a new, larger, color space defined by Rec. 2020. Does this new color space require RGB pixels of a different wavelength than current HDTV Rec. 709 pixels?
  • Are the displays coming out now ready for this new color space, or are they just Rec. 709 displays that happen to have more pixels?
  • Will the Sony 4K player, which I believe is the only consumer player right now, output 2020 at 10bits or just 709 at 8bits?
  • Are there ANY consumer displays that support the full spec right now? Any professional displays?

Thanks!
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post #2 of 47 Old 08-08-2013, 03:23 PM
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I think the Sony 4K sets with Triluminos will be the only ones that approach the BT.2020 colorspace just now.
I don't know that they have support for BT.2020 inputs - they may need an update, or external calibration device in-between the player and display for accurate color.

You will probably be able to calibrate JVC's projectors to the BT.2020 colorspace as well, as they typically have very wide gamuts. Probably the Mitsubishi Laservue DLPs too. (though they are not 4K) I doubt there's much else capable of it yet.
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post #3 of 47 Old 08-09-2013, 11:41 PM
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Doesn't really answer the question, but I'm pretty sure that if you buy *any* "4K" set today, you can probably count on it being "obsolete' in one way or the other if/when the dust settles on "4K/UHD" and programming becomes more available.

Been there, done it ... ain't gonna do the bleedin' this time. wink.gif
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post #4 of 47 Old 08-14-2013, 04:34 AM
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Originally Posted by HDTVChallenged View Post

Been there, done it ... ain't gonna do the bleedin' this time. wink.gif

+1
I still have both the $1200 1st gen Panny BD & $900 Toshiba HD-DVD players in their boxes sitting on a shelf & a Pio Elite RPTV with DVI sitting in a bedroom, not being used. yes, that DVI, the connection that only lasted ~2 yrs before being completely obsoleted rolleyes.gif

nope, dust will have to settle >> at minimum full support for HDMI 2.0 in TV & player + some non-proprietary content system, NOT Sony's "only in our sandbox" server = betamax 2.0 tongue.gif

been burned enough chasing HD

and CE companies want us to start the whole cycle again? rolleyes.gif

they need to adopt universal standards & delivery systems. instead, we have Sony being Sony...again.

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post #5 of 47 Old 08-26-2013, 03:46 PM
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Plus a million. And, when said dust settles there will not only be plenty of content, the prices will have come way down.

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post #6 of 47 Old 08-26-2013, 05:47 PM
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Quote:
AFAIK the UHD spec mandates a new, larger, color space defined by Rec. 2020. Does this new color space require RGB pixels of a different wavelength than current HDTV Rec. 709 pixels?

For LCD displays, color gamut is defined by the backlight. For an LCD to reach Rec 2020 some new type of backlight would need to be invented but that doesn't seem likely.
Quote:
Are the displays coming out now ready for this new color space, or are they just Rec. 709 displays that happen to have more pixels?

No. Some are better than Rec 709 but no where near Rec 2020.
Quote:
Will the Sony 4K player, which I believe is the only consumer player right now, output 2020 at 10bits or just 709 at 8bits?

It is definitely not using the Rec 2020 color gamut that is for sure. It is either outputting xvYCC or Rec 709.
Quote:
Are there ANY consumer displays that support the full spec right now? Any professional displays?

No. The only displays that could close to reproducing the Rec 2020 color gamut would be the Mitsubishi LaseVue TVs however they have been discontinued. The highest end professional display and projectors out there can only display DCI P3 which is smaller than Rec 2020.

Kit 4K (Database of 4K Displays), Kit 8K (Database of 8K Displays), Kit Display (General Display Information)
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post #7 of 47 Old 08-30-2013, 12:50 AM
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Originally Posted by NLPsajeeth View Post

The only displays that could close to reproducing the Rec 2020 color gamut would be the Mitsubishi LaseVue TVs however they have been discontinued.

Looks like Laservue is back, with Mitsubishi showing off a new 65" 4K LCD prototype.
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post #8 of 47 Old 08-31-2013, 10:33 AM
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Quote:
Originally Posted by LoKi128 View Post

Are the displays coming out now ready for this new color space, or are they just Rec. 709 displays that happen to have more pixels?
At the moment they just have higher resolution.

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Originally Posted by NLPsajeeth View Post

For LCD displays, color gamut is defined by the backlight. For an LCD to reach Rec 2020 some new type of backlight would need to be invented but that doesn't seem likely.
I think that RGB LED backlighting could go beyond the DCI P3 color space and that it could at least reach 80% of the Rec. 2020 color space.
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post #9 of 47 Old 03-22-2014, 10:22 AM
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Seeing the interview on Dolby Vision, it made me wonder which panel technologies are capable of rec.2020 color gamuts?

 

Can OLEDs do it? If they're a bit starved for brightness, I guess they will struggle to show a bright and fully saturated red for example, if it can't rely on the other sub pixels to boost brightness.


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post #10 of 47 Old 03-22-2014, 11:34 AM
 
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remember that you need 0 blacks to get most out of the higher color gamuts.
all colors starts from black.
otherwise the colors will look unreal/cartoonish even if the gamut is higher.

i have seen that effect with the Sony W9 that had a slight higher Green color than my Kuro in Color Space 1.
the blacklevel on the Sony wasnt good enough to display a true green color.

all colors on my Kuro looks way deeper with more punch to them compared to the Sony W9 with its higher Gamut.
black level is everything for colors

maybe a FALD LCD with Quantum Dots can fix rec2020.
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post #11 of 47 Old 03-22-2014, 12:02 PM
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Quote:
Originally Posted by Richard Paul View Post

Quote:
Originally Posted by LoKi128 View Post

Are the displays coming out now ready for this new color space, or are they just Rec. 709 displays that happen to have more pixels?
At the moment they just have higher resolution.

Quote:
Originally Posted by NLPsajeeth View Post

For LCD displays, color gamut is defined by the backlight. For an LCD to reach Rec 2020 some new type of backlight would need to be invented but that doesn't seem likely.
I think that RGB LED backlighting could go beyond the DCI P3 color space and that it could at least reach 80% of the Rec. 2020 color space.

I believe that both the Sony X950B and the Vizio Reference Series are claiming '80% of rec.2020'...
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post #12 of 47 Old 03-22-2014, 12:07 PM
 
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I no longer believe in corporate/marketing claims after what Panasonic pulled concerning DCI capabilities of its final plasmas.
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post #13 of 47 Old 03-22-2014, 03:21 PM
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Since the gamut is likely to vary greatly between displays, how will proper saturation be set using Rec 2020 test signals? With 709, better displays can exceed its gamut, and matrixing can be used to reduce it and possibly rotate the displayed primaries. Since the REC 2020 source can now exceed the the display's gamut, pure colors such as what's been used in color bars would be meaningless. I would think test signals representing various saturations that fall within display gamuts would be needed. The displays themselves would likely need to have the saturation boosted to match their limited gamut to Rec 2020 within their range, which tops out when a RGB channel approaches 0 - can't create negative light. Maybe Rec 2020 bars which represent 709 gamut would suffice. I guess that's part of the goal for Dolby Vision.
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post #14 of 47 Old 03-22-2014, 05:07 PM
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Originally Posted by TVOD View Post

Since the gamut is likely to vary greatly between displays, how will proper saturation be set using Rec 2020 test signals?
Dolby's plan is to use metadata for the new color in such a fashion that old rec. 709 displays will not see it at all, but new rec. 2020 displays can find and use it. Dolby claims they need only 20% bandwidth overhead for the extra data in a Dolby Vision program.

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post #15 of 47 Old 03-22-2014, 06:24 PM
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Originally Posted by Masterbrew2 View Post

Seeing the interview on Dolby Vision, it made me wonder which panel technologies are capable of rec.2020 color gamuts?
At the moment there is no independent way to test the displays so it depends on how honest the companies are. Even than it a moot point since the entire video processing chain would have to support the Rec. 2020 color space, from the HDMI input to the display panel, and at the moment it isn't supported by any of the video processing chips. It is unlikely that any of the consumer displays released this year will support it.

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Since the gamut is likely to vary greatly between displays, how will proper saturation be set using Rec 2020 test signals?
A few proposals have been accepted at the last few HEVC meetings that add metadata about the color gamut (the mastering display, the color primaries, the maximum brightness, etc...). Recently a proposal was made that allows for gamut mapping from wide color gamut video to HDTVs. Put together there will be a lot of information on gamut mapping though it will be up to the display manufacturers to decide how to use it since consumers might prefer vivid colors more than accuracy.

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Dolby's plan is to use metadata for the new color in such a fashion that old rec. 709 displays will not see it at all, but new rec. 2020 displays can find and use it. Dolby claims they need only 20% bandwidth overhead for the extra data in a Dolby Vision program.
While the HDR system from Dolby is efficient, considering that it has a maximum brightness of 10,000 nits, the problem with Dolby Vision is that it is mostly marketing. For example the only requirement for Dolby Vision is a minimum brightness of 400 nits and insiders in other forums say that the only color space that Dolby Vision products need to support is the Rec. 709 (HDTV) color space. Scalable video encoding has been around since the days of MPEG-2 but it is rarely used since it has problems with cost and video quality. A system based on native video content would be best since it would have better video quality and have lower costing video decoders.
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post #16 of 47 Old 03-22-2014, 06:49 PM
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A system based on native video content would be best since it would have better video quality and have lower costing video decoders.
Does "native video content" here mean content not somehow secondarily derived (like Dolby PLIIz) and not recorded by a camera? If so, please be advised that Dolby Vision is based on native video content. Or maybe your phrase means "not metadata"? If the last, why do you think metadata gives lower video quality or higher costing video decoders?

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post #17 of 47 Old 03-22-2014, 07:23 PM
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Does "native video content" here mean content not somehow secondarily derived (like Dolby PLIIz) and not recorded by a camera?
A video system in which the color space can be Rec. 2020 and that can use gamut mapping to decrease the wide color gamut video for Rec. 709 displays.

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Or maybe your phrase means "not metadata"? If the last, why do you think metadata gives lower video quality or higher costing video decoders?
Using enhancement data to increase the color space will require more complex decoders and a higher bit rate for the same video quality. Natively encoding video is simpler than trying to encode the differences between two different versions of a video stream. That is why video streaming websites like Netflix encode video streams at different bit rates instead of encoding a baseline video stream with multiple enhancement video streams. Of course CE companies might like the idea of enhancement data since it offers them the ability to sell a product soon and than sell an enhanced version of that product a year or two later.
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post #18 of 47 Old 03-22-2014, 09:17 PM
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Using enhancement data to increase the color space will require more complex decoders and a higher bit rate for the same video quality. Natively encoding video is simpler than trying to encode the differences between two different versions of a video stream.
I think there are two things wrong with this reasoning. (1) You've jumped to the conclusion that the differences between two streams would be encoded. Why think that? In the limiting case, both streams could be encoded separately and the unneeded one discarded. Then there would be no "lower video quality or higher costing video decoders". And the encoding of 6 audio streams in DD 5.1 compression does not simply encode difference streams.
(2) You're not considering the trade-offs. Dolby argues that their approach would allow enhanced video to be broadcast without any change in current broadcast regulations. If we had to wait for enhanced video as long as we did for the change to digital broadcasting, that would be really painful.

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post #19 of 47 Old 03-22-2014, 10:36 PM
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I think there are two things wrong with this reasoning. (1) You've jumped to the conclusion that the differences between two streams would be encoded. Why think that? In the limiting case, both streams could be encoded separately and the unneeded one discarded.
The baseline video stream can't be discarded and if you don't have the enhancement data than you aren't getting anything more than what is in the baseline video stream. Also the explanation that Dolby has given for Dolby Vision was that it uses two decoders that use a base layer and an enhancement layer.

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(2) You're not considering the trade-offs. Dolby argues that their approach would allow enhanced video to be broadcast without any change in current broadcast regulations. If we had to wait for enhanced video as long as we did for the change to digital broadcasting, that would be really painful.
I was thinking about 4K Blu-ray in which backward compatibility would not be a concern since they are hopefully making several improvements (which would include the hardware). As for ATSC 3.0 they have already announced that it will use a different physical signal and they are planning to finalize it in 2015. Also Dolby Vision is completely proprietary and doesn't even require displays to support a wider color gamut so their system is mainly about HDR.
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post #20 of 47 Old 03-23-2014, 12:05 AM
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Also Dolby Vision is completely proprietary and doesn't even require displays to support a wider color gamut so their system is mainly about HDR.
I'm not sure what this means. Are you talking about what conditions, if any, Dolby will impose on the use of the term "Dolby Vision"? I don't know anything about that, at all. Conceptually, wide gamut certainly is a part of Dolby Vision. From the reference you gave: "Dolby Vision is supporting the BT.2020 color space in full. Alternatively, it can also be configured to support the XYZ color space if needed for certain applications."

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post #21 of 47 Old 03-23-2014, 09:54 AM
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I'm not sure what this means. Are you talking about what conditions, if any, Dolby will impose on the use of the term "Dolby Vision"? I don't know anything about that, at all. Conceptually, wide gamut certainly is a part of Dolby Vision.
Wide color gamut support is optional with Dolby Vision. If you cut through the marketing the only requirement that Dolby ever mentions in their interviews is that a Dolby Vision display must support a minimum brightness of 400 nits. From what insiders have said on various forums the only requirement for Dolby Vision content is support for HDR. As such Dolby Vision is mainly an HDR system and a way to promote their patented perceptual gamma curve. Their HDR system sounds nice but something I dislike about a proprietary standard is that all the information comes from the company that is trying to promote it which can make it hard to separate the facts from the marketing.
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post #22 of 47 Old 03-23-2014, 10:09 AM
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If you cut through the marketing the only requirement that Dolby ever mentions in their interviews is that a Dolby Vision display must support a minimum brightness of 400 nits.
In the reference you just gave, I see this: "Dolby Vision works with a minimum of 12 bit per pixel up to 16 bit per pixel as needed." However, I'm not taking all the figures I see completely seriously, since Vizio Reference sets are supposed to have only 10 bit color, iirc.

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post #23 of 47 Old 03-23-2014, 10:41 AM
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Originally Posted by GregLee View Post

In the reference you just gave, I see this: "Dolby Vision works with a minimum of 12 bit per pixel up to 16 bit per pixel as needed." However, I'm not taking all the figures I see completely seriously, since Vizio Reference sets are supposed to have only 10 bit color, iirc.
That most likely refers to the bit depth of the Dolby Vision video signal when the base layer and enhancement layer are combined.
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post #24 of 47 Old 03-23-2014, 11:18 AM
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That most likely refers to the bit depth of the Dolby Vision video signal when the base layer and enhancement layer are combined.
Well, it wouldn't be Dolby Vision if the enhancement layer weren't combined. The context makes it clearer:
Quote:
Provide more details on the color space enabled by Dolby Vision. Is it BT 2020 or something else?

Dolby Vision is supporting the BT.2020 color space in full. Alternatively, it can also be configured to support the XYZ color space if needed for certain applications.

What bit depth do you support?

Dolby Vision works with a minimum of 12 bit per pixel up to 16 bit per pixel as needed.

Elsewhere I've seen 10 or 12 bits (per primary per pixel).

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post #25 of 47 Old 03-23-2014, 12:33 PM
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Quote:
Originally Posted by GregLee View Post

Quote:
Originally Posted by Richard Paul View Post

That most likely refers to the bit depth of the Dolby Vision video signal when the base layer and enhancement layer are combined.
Well, it wouldn't be Dolby Vision if the enhancement layer weren't combined. The context makes it clearer:
Quote:
Provide more details on the color space enabled by Dolby Vision. Is it BT 2020 or something else?

Dolby Vision is supporting the BT.2020 color space in full. Alternatively, it can also be configured to support the XYZ color space if needed for certain applications.

What bit depth do you support?

Dolby Vision works with a minimum of 12 bit per pixel up to 16 bit per pixel as needed.

Elsewhere I've seen 10 or 12 bits (per primary per pixel).

This is probably the computational precision - in the end the desired 'ideal' 16-bit-per-pixel image will almost certainly be mapped to the panel (rounded to the nearest 8 or 10 bit value, depending on panel precision).
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post #26 of 47 Old 03-23-2014, 05:57 PM
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Well, it wouldn't be Dolby Vision if the enhancement layer weren't combined. The context makes it clearer:
Dolby Vision supports features that are optional and the bit depth of the video signal wouldn't tell us the required bit depth for Dolby Vision displays (if there is a requirement). Dolby's perceptual gamma curve allows for a maximum brightness of 10,000 nits while in comparison Dolby Vision displays must support 400 nits. It is possible that we will see Dolby Vision displays that use 8-bit panels.
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post #27 of 47 Old 03-24-2014, 02:14 AM
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@Richard Paul. I asked a question in the thread on the podcast Scott had on Dolby Vision that you might be able to answer.

 

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They say that Dolby Vision will be delivered through an enhancement layer that adds about 20% bandwidth to an existing 8-bit rec.709 source. So those 20% will contain up to 4-6 extra stops of dynamic range, 50% more color space, and 10-bit dithering?

 

I know it won't have to add all these things simultaneously, only when they are required of the source, but it still seems like a bit of a tall order. I wonder what the compromises are.

 

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post #28 of 47 Old 03-24-2014, 02:19 PM
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I don't think a Dolby Vision signal can be said to contain a dynamic range or a color space, exactly. The dynamic range concerns what the camera sees and what the display shows, which one hopes will correspond, and similarly for the color space. In the signal itself, the brightest and dimmest shades are just two numbers -- not much bandwidth needed there. If there is a high dynamic range, it is due to the way those numbers are interpreted in the camera and the display. It's the number of gradations in between that may require extra bandwidth. For 10 bit color, by my count we get 876 grey levels, which is 876 combinations of equal parts of the 3 primaries. The Wikipedia article on Rec. 2020 says
Quote:
10-bits per sample Rec. 2020 uses video levels where the black level is defined as code 64 and the nominal peak is defined as code 940.[1] Codes 0-3 and 1,020-1,023 are used for the timing reference.[1] Codes 4 through 63 provide video data below the black level while codes 941 through 1,019 provide video data above the nominal peak.[1] [http://en.wikipedia.org/wiki/Rec._2020]

So the dynamic range is expressed in the signal for 10 bit color as 876 grey levels per pixel, and that is a high dynamic range if camera and display interpret the numbers as gradations going from a low nit number to a rather high nit number.

The color gamut will be wide if camera and display interpret the numbers in the signal in the right way.

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post #29 of 47 Old 03-24-2014, 05:16 PM
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Originally Posted by Masterbrew2 View Post

@Richard Paul. I asked a question in the thread on the podcast Scott had on Dolby Vision that you might be able to answer.
One problem with a proprietary standard is that we don't know what Dolby was referring to. That figure might only refer to adding HDR and it might be based on an optimistic video source.

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I don't think a Dolby Vision signal can be said to contain a dynamic range or a color space, exactly.
Dolby Vision uses a perceptual gamma curve, Dolby is hoping that it becomes a replacement for the traditional gamma curve, and of course it comes with a royalty. Dolby is promoting HDR because they are hoping to get a royalty on every future UHDTV.

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In the signal itself, the brightest and dimmest shades are just two numbers -- not much bandwidth needed there. If there is a high dynamic range, it is due to the way those numbers are interpreted in the camera and the display.
The perceptual gamma curve that Dolby uses goes up to 10,000 nits regardless of what brightness is used in the video.

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For 10 bit color, by my count we get 876 grey levels, which is 876 combinations of equal parts of the 3 primaries.
With the traditional gamma curve 12-bit video would be sufficient for 800 nits of brightness (which in my opinion is more than enough for consumer HDR displays).
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post #30 of 47 Old 03-25-2014, 05:34 AM
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Originally Posted by Richard Paul View Post

Dolby Vision uses a perceptual gamma curve, Dolby is hoping that it becomes a replacement for the traditional gamma curve, and of course it comes with a royalty. 

 

Can you explain what the perceptual gamma curve is, and how it differs from the traditional?


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