Color My TV World - AVS Forum
Forum Jump: 
 3Likes
  • 1 Post By JWhip
  • 1 Post By madshi
  • 1 Post By catonic
Thread Tools
post #1 of 29 Unread 08-01-2014, 01:01 PM - Thread Starter
AVS Special Member
 
Scott Wilkinson's Avatar
 
Join Date: Sep 2001
Location: Burbank, CA
Posts: 1,345
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 353 Post(s)
Liked: 1185
Color My TV World



Video guru Joe Kane talks about color in the UHDTV ecosystem, including the various possible color gamuts, color containers, "connectivity" (what he calls the signal path from image creation to the consumer), the color spectra of various light sources and display types, why BT.2020 isn't the best choice for a display gamut, metamerism, the importance of backward compatibility and why current UHDTVs and even HDTVs needn't become obsolete, answers to chat-room questions, and more.


Like AVS Forum on Facebook
Follow AVS Forum on Twitter
+1 AVS Forum on Google+

Scott Wilkinson
AVS Editor

Last edited by Scott Wilkinson; 08-01-2014 at 01:14 PM.
Scott Wilkinson is offline  
Sponsored Links
Advertisement
 
post #2 of 29 Unread 08-02-2014, 06:22 AM
AVS Special Member
 
JWhip's Avatar
 
Join Date: Jun 2001
Location: Wayne, PA
Posts: 4,300
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 230 Post(s)
Liked: 286
Scott, that was a fine thought provoking interview. It would have been great to see Joe Kane at the shootout to explore the issues he raised here but I will be away. I did have one question about the connectivity issue he raised. Just what is it that will carry all of these different streams to the display, so it can pick out the rec. 709, or P3 or whatever color gamut is available? Given that that has to be a rather large stream, can HDMI 2.0 do it? I would think display port will be able to, but will any 4K Blu-ray that is eventually announced support display port? I would think that the studios may have an issue with that. Will we need yet another HDMI spec to handle this level of "connectivity"? Thanks.
JWhip is offline  
post #3 of 29 Unread 08-02-2014, 08:20 AM
AVS Special Member
 
madshi's Avatar
 
Join Date: May 2005
Posts: 5,482
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 140
Quote:
Originally Posted by JWhip View Post
I did have one question about the connectivity issue he raised. Just what is it that will carry all of these different streams to the display, so it can pick out the rec. 709, or P3 or whatever color gamut is available? Given that that has to be a rather large stream, can HDMI 2.0 do it?
I believe the TV will tell the source device which native gamut (RGB primary coordinates) it has, and the source device will perform the necessary corrections/conversions. Which means that there's no increase in bandwidth at all.

Quote:
Originally Posted by Scott Wilkinson View Post
Video guru Joe Kane talks about color in the UHDTV ecosystem, including the various possible color gamuts, color containers, "connectivity" (what he calls the signal path from image creation to the consumer), the color spectra of various light sources and display types, why BT.2020 isn't the best choice for a display gamut, metamerism, the importance of backward compatibility and why current UHDTVs and even HDTVs needn't become obsolete, answers to chat-room questions, and more.
Very nice one, thanks. For once I've barely anything to disagree with. One thing I don't understand is the following, though:

When using a container/carrier that is large enough (ACES or XYZ), all colors that are visible to the human eye can already be represented by the container, with the usual 3 color system (RGB). So why would Joe want to go for a 6 color system? If the ACES/XYZ container can already hold all visible colors, what advantage would a 6 color system bring in addition to that?
madshi is offline  
post #4 of 29 Unread 08-02-2014, 08:57 AM
AVS Special Member
 
JWhip's Avatar
 
Join Date: Jun 2001
Location: Wayne, PA
Posts: 4,300
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 230 Post(s)
Liked: 286
[QUOTE=madshi;26236705]I believe the TV will tell the source device which native gamut (RGB primary coordinates) it has, and the source device will perform the necessary corrections/conversions. Which means that there's no increase in bandwidth at all.

That may very well be the case. However, that was not well explained.
Masterbrew2 likes this.
JWhip is offline  
post #5 of 29 Unread 08-02-2014, 09:55 AM
AVS Special Member
 
thorr's Avatar
 
Join Date: Jan 2001
Location: San Diego, CA USA
Posts: 1,703
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 15
Very interesting discussion. My major question regarding this "connectivity" idea is how much storage space / bandwidth does it take to deliver all of that content all the way to the consumer? I am thinking it has to be astronomical. I understand that it would be downconverted to whatever display technology the consumer has just before the display device, but it still would need to be delivered into the home of the consumer. Currently that delivery method would need to be something like blu-ray disc, streaming, hard drives or backup tapes (LTO, etc). I think hot swap hard drives or possibly backup tapes are the only storage medium that would be viable. The cheapest 1 TB hard drive I could find on Amazon with a quick search is about $55, and 2 TB is about $82. By the time this would come to the consumer, it might be $25 per hard drive. Streaming could work with this by requesting the best signal the display is capable of with the available bandwidth, but it would require massive processing at the carrier's facilities to handle all of the various consumers specific needs.

Another question would be regarding all of the different manufacturers of the capture devices. They would all most likely have different capabilities and would store there content in their "native" format for that capture device. Dealing with all of the various capture devices and making a standard to handle all of them that they can store to and be interpreted by a single playback device on the consumer side might be difficult as well.

I really do like the concept and I get that it makes the sky the limit. I also wonder about going the other way where you have a much better display than the content is stored with (like rec709). I suppose it would be up to the display to upconvert the content (color, etc.) or limit the color so it looks like rec709 on the display.

Mike
thorr is offline  
post #6 of 29 Unread 08-02-2014, 12:05 PM
AVS Special Member
 
JWhip's Avatar
 
Join Date: Jun 2001
Location: Wayne, PA
Posts: 4,300
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 230 Post(s)
Liked: 286
My point exactly thorr only stated more precisely.
JWhip is offline  
post #7 of 29 Unread 08-02-2014, 10:39 PM
Senior Member
 
eclipsegt's Avatar
 
Join Date: Mar 2010
Location: Seattle
Posts: 291
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 15 Post(s)
Liked: 60
Very interesting video. Ever sense CES 2014 I've been fascinated by wider color gamut. It's really the next big thing that the TV business needs. Our current UHD is great but the fact is that there isn't much of a difference when sittings at a normal distance. Wider color is something you can see from any distance. However, this video has brought up some great points about the possible issues of Rec.2020.

Perhaps jumping to Rec.2020 is not the best option. IMO bringing P3 to consumer TVs with content to take advantage of it would be a great upgrade. Sure id like something higher than P3 such as the Adobe RBG, but at this point anything is better than the ancient Rec.709 that we are limited to now.

One thing is for sure, CES 2015 will be very interesting. With the disagreement in color standards, the development of HDR and the issues with 4K Blu-Ray, this UHD system seems to be off to a rocky start. We have the technology but we need the displays and content.
eclipsegt is online now  
post #8 of 29 Unread 08-03-2014, 12:51 AM
AVS Special Member
 
Richard Paul's Avatar
 
Join Date: Sep 2004
Posts: 6,959
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 29
I am not surprised that Joe Kane believes that DCI P3 would be best for UHDTV since that is what the studios are promoting. While some people can notice a difference with a pure spectral color it is a very small difference (DCI P3 has a pure spectral red and no one complains about it).

The studios are doing their best to kill the Rec. 2020 color space since if it is chosen for UHDTV than the studios would have to upgrade their equipment (and that equipment costs a lot). While the Rec. 2020 space is large there are several display technologies (laser projection, LCD, and OLED) that are capable of showing over 90% of it. For example Nanosys made an LCD display that could show 91% of the Rec. 2020 color space and if it had better color filters it could have shown 97%.
Richard Paul is offline  
post #9 of 29 Unread 08-03-2014, 12:58 AM
AVS Special Member
 
madshi's Avatar
 
Join Date: May 2005
Posts: 5,482
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 140
Quote:
Originally Posted by Richard Paul View Post
I am not surprised that Joe Kane believes that DCI P3 would be best for UHDTV
Actually, AFAIU he seems to favor using a large container/carrier like ACES (which is even bigger than BT.2020), which is then converted to whatever the display can do.
madshi is offline  
post #10 of 29 Unread 08-03-2014, 02:18 AM
Senior Member
 
Marc Wielage's Avatar
 
Join Date: Jul 2000
Location: Hollywood, USA
Posts: 458
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 234 Post(s)
Liked: 125
I think Rec2020 is total overkill for a lot of stuff, particularly in that very few cameras can capture this standard, and nobody is set up to transfer old films in this standard. The joke in the mastering business is that they call it "Rec2020" because 2020 is probably the year all the kinks will be worked out of the standard.

I'd be happy if people could just see mildly-compressed HD images in proper Rec709 at home. That actually looks pretty good, though I'd agree with Joe that it could stand improving... someday. P3 is very doable, but it's not gigantically and unsubtly different from Rec709:



As you can see in the diagram, getting really strong greens is really hard. The problem with trying to reproduce P3 is that most of that work today is being done with projectors, and there's a lot of reasons why P3 D-Cinema work doesn't work well with monitors. You get an entirely different perception seeing a large 20' image on a projection screen than you do on (say) a 50-60" monitor. It's a totally different experience.

There's a lot of good stuff on color space and color management in general in this free SIGGRAPH tech paper, if anybody wants to read it:

https://raw.githubusercontent.com/je..._Color_VES.pdf

Be warned there's a lotta math and a lot of photos with circles and arrows on the back of each one, but the essential science is covered in great detail. This is not a simple subject, and trying to cram this technology in a $695 consumer monitor is fraught with problems.
Marc Wielage is offline  
post #11 of 29 Unread 08-03-2014, 07:20 AM
Advanced Member
 
mightyhuhn's Avatar
 
Join Date: Nov 2013
Posts: 716
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 314 Post(s)
Liked: 115
why not simply give them free access to multiply colorspaces.
for example P3, 709 and 2020. the playback device has to be able to transform them all down to 709 so compatibility is given or even better it has to be able to transform all to all supported colorspaces. studios cna now use the best fitting colorspace. if you encode a source with only 709 transform to 2020 the encoder can't use the full colordeep because a lot possibilities are never used so encoding it as 709 should result in better quality.

forcing bt 2020 doesn't sound like a good choice to me. you need more space to store those informations that can't be displays in the next ~10 years and high bit deep is a must have.

it is known that high bit deep can help to compress lower bit deep sources better but in this case all information stored are fully used as intended later on and needed.
mightyhuhn is online now  
post #12 of 29 Unread 08-03-2014, 10:31 AM
AVS Addicted Member
 
mark haflich's Avatar
 
Join Date: Dec 2000
Location: brookeville, maryland, usa
Posts: 20,239
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 623 Post(s)
Liked: 585
quote=eclipsegt;26252313]Very interesting video. Ever sense CES 2014 I've been fascinated by wider color gamut. It's really the next big thing that the TV business needs. Our current UHD is great but the fact is that there isn't much of a difference when sittings at a normal distance. Wider color is something you can see from any distance. However, this video has brought up some great points about the possible issues of Rec.2020.

Perhaps jumping to Rec.2020 is not the best option. IMO bringing P3 to consumer TVs with content to take advantage of it would be a great upgrade. Sure id like something higher than P3 such as the Adobe RBG, but at this point anything is better than the ancient Rec.709 that we are limited to now.

One thing is for sure, CES 2015 will be very interesting. With the disagreement in color standards, the development of HDR and the issues with 4K Blu-Ray, this UHD system seems to be off to a rocky start. We have the technology but we need the displays and content.[/quote]

How can you state and believe OUR current UHD is great? As established by the industry's trade association, CEA, in September a set qualifies to be called a UHD set if it displays 3840 x 2160, it can upscale anything to that, it has an aspect ratio of 1.78 or higher, it can handle 8 bits and it does rec 709. Has to be able to input and display 3840 x 2160 at 24, 30 and 60 fps and have at least one HDMI input. And it must be protected with HDCP 2.2 or its equivalent. HD with more pixels. That's really great.

Will the studios allow P3 for the home? They want to give commercial theaters something better than they give home consumers. My guess is that the coming 4K blu ray standard will be a space not as big as DCI. But the consumer really doesn't care. I can not remember anyone ever posting that they saw a movie at a DCI theater and then watched it at home on blu ray and they noticed less colors at home.

If you can't understand why rec 2020 is bad, watch the video again. The bands are way too narrow and when color is generated with narrow RGB a broad cross section of people will see the colors quite differently from their neighbor.

P3 would be great and would make post work conversion to a 4K blu ray standard that adopted P3 a lot easier and much more cheaper.

Remember when the 4K blu ray standard is announced, and it will be announced I think no later than CES, it will be a political decision and not what idealist want.

Mark Haflich
markhaflich@yahoo.com
call me at: 240 876 2536

Last edited by mark haflich; 08-08-2014 at 06:39 AM.
mark haflich is online now  
post #13 of 29 Unread 08-03-2014, 09:04 PM
AVS Special Member
 
Richard Paul's Avatar
 
Join Date: Sep 2004
Posts: 6,959
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 29
Quote:
Originally Posted by madshi View Post
Actually, AFAIU he seems to favor using a large container/carrier like ACES (which is even bigger than BT.2020), which is then converted to whatever the display can do.
Joe Kane did say that he would prefer DCI P3 over Rec. 2020 and for cost reasons those are the only two color spaces that could be used in consumer equipment. Any of the professional container formats (ACES, XYZ, etc...) would be expensive and the additional calculations would make them unsuitable for real time graphics.


Quote:
Originally Posted by mightyhuhn View Post
why not simply give them free access to multiply colorspaces.
for example P3, 709 and 2020. the playback device has to be able to transform them all down to 709 so compatibility is given or even better it has to be able to transform all to all supported colorspaces
HEVC will soon have the ability to remap the Rec. 2020 color space to any other color space (DCI P3, Rec. 709, etc...).


Quote:
Originally Posted by mark haflich View Post
If you can't understand why rec 2020 is bad watch the video again. The bands are way to narrow and when color is generated with narrow RGB a broad cross section of people will see the colors quite differently from their neighbor.
That is a rumor and if pure spectral colors had such a problem than it would also have been a problem for DCI P3. Video experts spent years developing the Rec. 2020 standard and tested the color space using laser projectors.
Richard Paul is offline  
post #14 of 29 Unread 08-04-2014, 03:02 AM
AVS Special Member
 
madshi's Avatar
 
Join Date: May 2005
Posts: 5,482
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 140
Quote:
Originally Posted by Richard Paul View Post
Joe Kane did say that he would prefer DCI P3 over Rec. 2020
Joe hates Rec. 2020 when used in a specific way (see (1)), but not when used in a different way (see (2)). I'm not sure if you fully got that distinction. You probably just heard the part where he complained about (1), but I think you might have missed the part where he talked about (2).

(1) Joe Kane doesn't like Rec. 2020 as a format that display manufacturers would try to achieve or calibrate to. The reason for that is that he claims the wavelength coverage is bad. Which honestly I don't understand, but I probably don't have the necessary knowledge to understand it. So as far as using Rec. 2020 as a calibration/display technology format is concerned, you're most definitely right and Joe Kane absolutely hates Rec. 2020.

(2) However, everything changes if you use Rec. 2020 as a carrier/container. Joe's ideal solution would be to use a large container which then downconverts to what the display can do. And Rec. 2020 comes much nearer to Joe's ideal solution than P3, *if* Rec. 2020 is just used as a container. So from this aspect Joe absolutely likes Rec. 2020. However, he likes ACES even more, because it's tried and proven and even bigger than Rec. 2020. Why invent a new container if there's already one which is working great? This is the reason why Joe isn't into Rec. 2020 as much as we might expect.

Quote:
Originally Posted by Richard Paul View Post
Any of the professional container formats (ACES, XYZ, etc...) would be expensive and the additional calculations would make them unsuitable for real time graphics.
How would they be expensive? Are you talking about license costs or development costs or computational demands? From what I can see, calculations should be a easy for a decent graphics processing chip.
madshi is offline  
post #15 of 29 Unread 08-04-2014, 02:41 PM
Member
 
Matthias Hutter's Avatar
 
Join Date: Jan 2009
Posts: 56
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
Liked: 33
expensive in bandwidth. Currently, "full" ACES uses 16 bit OpenEXR with 2:1 losless compression.
Matthias Hutter is offline  
post #16 of 29 Unread 08-04-2014, 07:44 PM
AVS Special Member
 
Richard Paul's Avatar
 
Join Date: Sep 2004
Posts: 6,959
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 29
Quote:
Originally Posted by madshi View Post
Joe hates Rec. 2020 when used in a specific way (see (1)), but not when used in a different way (see (2)). I'm not sure if you fully got that distinction. You probably just heard the part where he complained about (1), but I think you might have missed the part where he talked about (2).

(1) Joe Kane doesn't like Rec. 2020 as a format that display manufacturers would try to achieve or calibrate to. The reason for that is that he claims the wavelength coverage is bad. Which honestly I don't understand, but I probably don't have the necessary knowledge to understand it. So as far as using Rec. 2020 as a calibration/display technology format is concerned, you're most definitely right and Joe Kane absolutely hates Rec. 2020.
The video experts who developed the Rec. 2020 standard considered several color spaces over the course of years and this rumor about it only started after the studios realized that the UHDTV standard had been released (at which point they started to advocate for DCI P3). I think the timing of the rumor is a bit suspicious and if using a pure spectral color was a problem than it would also have been a problem for DCI P3.


Quote:
Originally Posted by madshi View Post
(2) However, everything changes if you use Rec. 2020 as a carrier/container. Joe's ideal solution would be to use a large container which then downconverts to what the display can do. And Rec. 2020 comes much nearer to Joe's ideal solution than P3, *if* Rec. 2020 is just used as a container. So from this aspect Joe absolutely likes Rec. 2020. However, he likes ACES even more, because it's tried and proven and even bigger than Rec. 2020. Why invent a new container if there's already one which is working great? This is the reason why Joe isn't into Rec. 2020 as much as we might expect.
ACES uses half precision floating point values which are a lot harder to compress than integer values. ACES has a fantastic dynamic range and very high precision but it is also very expensive.


Quote:
Originally Posted by madshi View Post
How would they be expensive? Are you talking about license costs or development costs or computational demands? From what I can see, calculations should be a easy for a decent graphics processing chip.
Computational cost would be a problem for all the professional containers since every additional conversion increases the cost and most of the professional containers were designed for very high bit rates. The Rec. 2020 color space was designed for consumer video, uses 10-bit/12-bit integer values, and uses the standard D65 white point (which is also used by HDTV, SDTV, and sRGB).
Richard Paul is offline  
post #17 of 29 Unread 08-05-2014, 12:09 AM
AVS Special Member
 
madshi's Avatar
 
Join Date: May 2005
Posts: 5,482
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 140
Quote:
Originally Posted by Matthias Hutter View Post
expensive in bandwidth. Currently, "full" ACES uses 16 bit OpenEXR with 2:1 losless compression.
Of course for 4K Blu-Ray / UHD we would use h264/HEVC with 16bit integer compression, instead of lossless compression. That should fully remove any bandwidth problems.

Quote:
Originally Posted by Richard Paul View Post
ACES uses half precision floating point values which are a lot harder to compress than integer values. ACES has a fantastic dynamic range and very high precision but it is also very expensive.
There's no problem converting floating point <-> integer. It should be easy to use ACES, but store the data in 16bit integer instead of floating point. Actually 16bit integer has more precision than half precision floating point, and HEVC already supports 16bit integer, and it compresses with very good efficiency. Ateme has published some papers which (somewhat surprisingly) show that increasing the encoding bitdepth helps compression efficiency with h264 instead of harming it. Meaning encoding 16bit integer should need ever so slightly less bitrate than encoding 8bit.

Last edited by madshi; 08-05-2014 at 12:12 AM.
madshi is offline  
post #18 of 29 Unread 08-05-2014, 05:15 AM
Advanced Member
 
mightyhuhn's Avatar
 
Join Date: Nov 2013
Posts: 716
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 314 Post(s)
Liked: 115
if you encode a 8 bit rec 709 in 10 bit it is normally better compressed true. but things change here if you take a rec 709/p3 source and change it to ACES and store it in 16 bit some bits are never ever used.
ACES is so much bigger that over 50% of the possibilities in the 16 bit are never used most likely even more. so HEVC has to encode 16 bit data that doesn't make use of the full 16 bit the bit for the highes number is never ever used because the colorpsace is so much bigger. a 8 bit source encoded in 10 or even higher bit deep makes full use of extra bits.
mightyhuhn is online now  
post #19 of 29 Unread 08-05-2014, 06:14 AM
AVS Special Member
 
madshi's Avatar
 
Join Date: May 2005
Posts: 5,482
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 140
True, but I don't think that would negatively affect compression efficiency in any way, so it shouldn't be a problem at all.
madshi is offline  
post #20 of 29 Unread 08-05-2014, 06:45 AM
Advanced Member
 
mightyhuhn's Avatar
 
Join Date: Nov 2013
Posts: 716
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 314 Post(s)
Liked: 115
i'm pretty sure bt 709 source encoded in 16 bit is better compressed as a bt 709 source encoded in 16 bit in ACES. don't forget the informations are 50 % or even more important in ACES else in bt 709 and i'm pretty sure the HEVC encoder doesn't know that.
and this alone is a huge deal. 10 bit decoding is already a lot slower than 8 bit decoding 16 bit will be really hard and ASIC going to be expensive a no go for something for the masses.

and it's know that 8 bit source are better compressed in 10 bit.
if this is still the case with 16 bit is not 100 % clear yet. and the "trick in 10 bit encoding is that first the lower bits are changed because the lower bit information aren't important but with a bigger colorsapce they get a lot more important so it does the opposite of what high bit deep does to 8 bit sources.

just theoretical and this is worth testing i my opinion. and we aren't missing a lot of tools to test this "soon".
mightyhuhn is online now  
post #21 of 29 Unread 08-05-2014, 10:03 AM
Member
 
Plutotype's Avatar
 
Join Date: Sep 2010
Posts: 77
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Liked: 15
Quote:
Originally Posted by madshi View Post
One thing I don't understand is the following, though:

When using a container/carrier that is large enough (ACES or XYZ), all colors that are visible to the human eye can already be represented by the container, with the usual 3 color system (RGB). So why would Joe want to go for a 6 color system? If the ACES/XYZ container can already hold all visible colors, what advantage would a 6 color system bring in addition to that?
From I have read, ACES or XYZ is not a colour space. Its a postproduction carrier and it uses metadata, which are essential for "showing" the image in Rec.709, P3, whatever. It covers whole CIE diagram, so that any colour space can be derived from it. If 6 colors would be in such standard, no problem.

Last edited by Plutotype; 08-05-2014 at 10:22 AM.
Plutotype is offline  
post #22 of 29 Unread 08-05-2014, 10:37 AM
Member
 
Plutotype's Avatar
 
Join Date: Sep 2010
Posts: 77
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Liked: 15
According to this document about ACES:
https://www.oscars.org/science-techn...ESOverview.pdf
they use RGB floating point for digital cameras and 16-bit for material from the scanner.

Regarding HEVC, I would be very interested to see such calculation for 12 or 16-bit / 4:4:4 / 3840 x 2160 24fps before compression and after compression.
I have used 16-bit as a option because simple logic tells me, that if Rec.709 needs at least 10-12bits to eliminate banding and brings things at least where they should be, 12-bit would be superb for P3. Rec.2020 may need 16-bits because now we would need to quantize a much more color information. Im writing this because using 12-bits vs using 16-bits 4:4:4 in 2160p matematically should make huge difference in terms of required connectivity for a single cable.
Plutotype is offline  
post #23 of 29 Unread 08-05-2014, 10:42 AM
AVS Special Member
 
madshi's Avatar
 
Join Date: May 2005
Posts: 5,482
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 140
Quote:
Originally Posted by mightyhuhn View Post
i'm pretty sure bt 709 source encoded in 16 bit is better compressed as a bt 709 source encoded in 16 bit in ACES. don't forget the informations are 50 % or even more important in ACES else in bt 709 and i'm pretty sure the HEVC encoder doesn't know that.
I believe it will make no difference. The encoding efficiency improvements of using a higher bitdepth source comes from having lower rounding errors inside the encoder math, and from the content having finer gradations which makes the image easier to "understand" for the encoder. Sure, when using a large color space, you might lose a bit of precision. So maybe a 16bit ACES source will compress similar to how a 14-15bit BT.709 source would compress. Which is a very very small difference.

Quote:
Originally Posted by mightyhuhn View Post
10 bit decoding is already a lot slower than 8 bit decoding 16 bit will be really hard and ASIC going to be expensive a no go for something for the masses.
I disagree. 8bit was easy. 10bit is not a size which is often used in the computer world. 16bit is a much more natural number for computers. 8bit = 1byte. 16bit = 2byte. 10bit = 1.25byte. 10bit is a really odd number, as is 12bit. I don't think making 16bit ASICs is much more difficult or expensive than making 10bit ASICs. Of course anything more than 8bit is more expensive than 8bit. But I think 16bit will only be marginally more difficult than 10bit.

Quote:
Originally Posted by mightyhuhn View Post
and it's know that 8 bit source are better compressed in 10 bit.
if this is still the case with 16 bit is not 100 % clear yet.
Yes, it is. As I said, Ateme has written papers about this.

Quote:
Originally Posted by Plutotype View Post
From I have read, ACES or XYZ is not a colour space. Its a postproduction carrier and it uses metadata, which are essential for "showing" the image in Rec.709, P3, whatever. It covers whole CIE diagram, so that any colour space can be derived from it. If 6 colors would be in such standard, no problem.
http://en.wikipedia.org/wiki/CIE_1931_color_space

"[...] the CIE 1931 RGB color space and CIE 1931 XYZ color space are the first mathematically defined color spaces."

In any case, I never said that using 6 colors would be a problem. I just don't understand the benefits of using 6 colors (for encoding / transport).

Quote:
Originally Posted by Plutotype View Post
I have used 16-bit as a option because simple logic tells me, that if Rec.709 needs at least 10-12bits to eliminate banding and brings things at least where they should be, 12-bit would be superb for P3. Rec.2020 may need 16-bits because now we would need to quantize a much more color information.
FWIW, people often forget that the banding which is most visible to our eyes is luma banding. And the luma channel doesn't care about the source gamut. Whether we use BT.709 or BT.2020, the luma channel still starts at black and ends at white. With 12bit there should be zero visible (luma) banding left. Regardless of the color space. The situation may be different if you compress RGB instead of YCbCr, though. Which is why I'd like to see YCbCr compression to be used - unless we get 16bit, then it shouldn't matter.

Last edited by madshi; 08-05-2014 at 10:47 AM.
madshi is offline  
post #24 of 29 Unread 08-05-2014, 10:50 AM
Newbie
 
Join Date: Aug 2014
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 0
yep.By the time this would come to the consumer, it might be $25 per hard drive. Streaming could work with this by requesting the best signal the display is capable of with the available bandwidth, but it would require massive processing at the carrier's facilities to handle all of the various consumers specific needs.[IMG]http://*******/OSI1pM[/IMG]
nectetwees is offline  
post #25 of 29 Unread 08-05-2014, 11:35 AM
Advanced Member
 
mightyhuhn's Avatar
 
Join Date: Nov 2013
Posts: 716
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 314 Post(s)
Liked: 115
Quote:
Originally Posted by madshi View Post
FWIW, people often forget that the banding which is most visible to our eyes is luma banding. And the luma channel doesn't care about the source gamut. Whether we use BT.709 or BT.2020, the luma channel still starts at black and ends at white. With 12bit there should be zero visible (luma) banding left. Regardless of the color space. The situation may be different if you compress RGB instead of YCbCr, though. Which is why I'd like to see YCbCr compression to be used - unless we get 16bit, then it shouldn't matter.
wasn't YCbCr encoding more efficient too.

the plan in DP 1.3 is to use the YCoCg colorspace for 8k to >visually< lossless compress the stream. i don't think they choice something else from RGB for fun.

http://www.vesa.org/wp-content/uploa...DSC-ETP200.pdf
http://jcgt.org/published/0001/01/02/paper.pdf

Quote:
and HEVC already supports 16bit integer
do you mean the 16 bit internal or did they finish true 16 output?

i have only seen x265 comparison but in these cases 10 bit or 8 bit doesn't made a lot of difference and the internal 16 doesn't made a huge difference too.
i'm totally aware that this encoder is young and will get better over the time but the the nearly zero difference between 8 and 10 bit with 16bbp internal precision makes me worry.

Quote:
Yes, it is. As I said, Ateme has written papers about this.
i think you posted a link about that in another thread about UHD.
it was only about h264 right?
i search for it later
mightyhuhn is online now  
post #26 of 29 Unread 08-05-2014, 11:59 AM
AVS Special Member
 
madshi's Avatar
 
Join Date: May 2005
Posts: 5,482
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Liked: 140
AFAIK, the July 2014 HEVC meeting finalized a lot of things they were working on, including full 16bit support etc. From what I've read, HEVC compresses 10bit better than 8bit, too, same as h264, but this is just what I read "somewhere on the internet". The Ateme papers are about h264.
Plutotype likes this.
madshi is offline  
post #27 of 29 Unread 08-09-2014, 11:41 AM
AVS Special Member
 
Richard Paul's Avatar
 
Join Date: Sep 2004
Posts: 6,959
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 29
Quote:
Originally Posted by madshi View Post
There's no problem converting floating point <-> integer. It should be easy to use ACES, but store the data in 16bit integer instead of floating point. Actually 16bit integer has more precision than half precision floating point, and HEVC already supports 16bit integer, and it compresses with very good efficiency.
If it doesn't use 16-bit floating point but instead uses some other encoding method than it would no longer be ACES but would instead be a new container format. 16-bit floating point is used for ACES due to the dynamic range it allows and here is a link to the OpenEXR website that explains how it works. There are newer ways to encode HDR video such as the recently released Dolby perceptual quantifier and here is a link to an article that explains why 12-bit video is sufficient for HDR when using a perceptual encoding method. That is why all of the 16-bit video profiles in HEVC are Intra only profiles since the companies that made HEVC think that future consumer video will be either 10-bit video or 12-bit video.


Quote:
Originally Posted by Plutotype View Post
Rec.2020 may need 16-bits because now we would need to quantize a much more color information.
Rec. 709 completely eliminates color banding with 10-bit video and 12-bit video would have 4 times the precision for each color. 12-bit video is more than enough for the Rec. 2020 color space and some companies have argued that 10-bit video would be good enough (since 8-bit video is used for current consumer video).


Quote:
Originally Posted by madshi View Post
8bit was easy. 10bit is not a size which is often used in the computer world. 16bit is a much more natural number for computers. 8bit = 1byte. 16bit = 2byte. 10bit = 1.25byte. 10bit is a really odd number, as is 12bit. I don't think making 16bit ASICs is much more difficult or expensive than making 10bit ASICs.
Every transistor in a hardware decoder adds to the cost so increasing the bit depth does increase the cost of hardware decoders. The higher the bit depth of a hardware decoder the more transistors needed and the more memory bandwidth needed.

Last edited by Richard Paul; 08-10-2014 at 09:07 PM.
Richard Paul is offline  
post #28 of 29 Unread 08-22-2014, 11:30 PM
Senior Member
 
catonic's Avatar
 
Join Date: Feb 2008
Posts: 292
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 66 Post(s)
Liked: 86
Here is a link to one of Joe Kane's articles on UHD:

http://www.buschhometheater.com/wp/w...-19Mar2014.pdf
Marc Wielage likes this.
catonic is online now  
post #29 of 29 Unread 08-23-2014, 02:17 AM
Senior Member
 
Marc Wielage's Avatar
 
Join Date: Jul 2000
Location: Hollywood, USA
Posts: 458
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 234 Post(s)
Liked: 125
Quote:
Originally Posted by catonic View Post
Here is a link to one of Joe Kane's articles on UHD...
That's a very interesting article -- thanks much for sharing it.
Marc Wielage is offline  
Reply AVS Forum Podcasts

Tags
frontpage , Home Theater Geeks



Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off