What is Wide Colour Gamut (WCG)? - article discussion

Hey @Steve Withers that was a great article and very informative as others have said. Really filled in some knowledge gaps. Couple of questions if I may:

You mention Chroma Sub-sampling. I've seen these ratios x:x:x before but have no understanding of it all means. Is this something that is exclusive to Hayley Davidson riders with all that chrome, or is this significant to the rest of us? Or is it best left to one side and embrace matte black!?!

Call it irrational fear or not, as TVs are getting capable of brighter and brighter images, I wonder if we are going to have our retinas burnt out at some point! Whilst indoors with light levels much lower than the great outdoors in bright sunshine, our irises open to allow more light to travel through our pupils. Does this make our eyes more sensitive and subject to potential damage from HDR levels of strobing or other extremely dynamic effects? I wonder if going for OLED would be a good thing just because they're not capable of going beyond 600 nits yet, so a limitation becomes a good safety feature. What are your thoughts here?
 
I have never, in twenty years, been in a design studio where anyone had any idea about display calibration or colour management.

Jesus, that's scary. What do they teach people in art/design colleges at all these days! Seems the lecturers are as clueless as the students - most likely hippy painters with no tech knowledge at all. Those design studios must be sending out some awfully badly coloured stuff then - how do clients/printers never complain about colours being all over the place? I knew all about color management and calibration all the way back in the Amiga 1200 days with print management software I bought and included excellent over 100 page manual ***!!

I think i did my isf training with you, and i only just followed this
Also annoying that I understand all that (including Mannis comments perfectly) and you only just followed it, and yet you are supposedly ISF certified and I am not (because it costs shed loads to get the certification)
 
I went on Pier's course that was organised through AVF some years ago. That probably helped me understand this article somewhat. I can understand how it could be difficult for some to understand, this is after all a highly technical area.
 
You mention Chroma Sub-sampling. I've seen these ratios x:x:x before but have no understanding of it all means. Is this something that is exclusive to Hayley Davidson riders with all that chrome, or is this significant to the rest of us? Or is it best left to one side and embrace matte black!?!

Call it irrational fear or not, as TVs are getting capable of brighter and brighter images, I wonder if we are going to have our retinas burnt out at some point! Whilst indoors with light levels much lower than the great outdoors in bright sunshine, our irises open to allow more light to travel through our pupils. Does this make our eyes more sensitive and subject to potential damage from HDR levels of strobing or other extremely dynamic effects? I wonder if going for OLED would be a good thing just because they're not capable of going beyond 600 nits yet, so a limitation becomes a good safety feature. What are your thoughts here?
Like the video bit depth, the chroma sub-sampling is related to the colour gamut but outside the scope of the article. However essentially chroma sub-sampling is a way of compressing colour data by taking advantage of how the human eye works. We are very good at noticing differences in luminance (brightness) but not so good when it comes to chroma (colour). So if a 4:4:4 signal is basically uncompressed with a full luminance channel (the first 4) and two full chroma channels (the second and third 4s) then a 4:2:0 (which is what Blu-ray and Ultra HD Blu-ray use) delivers the full luminance channel, half the first chroma channel and none of the second chroma channel, which reduces the bandwidth by half compared to a 4:4:4 signal. The player can then recover much of the encoded chroma information and output the signal as 4:2:2 or in some cases like the Panasonic UB900 as 4:4:4. It won't have the fidelity of an original signal that was actually encoded at 4:4:4 but the differences shouldn't be perceptible.

In regards to your query about brightness, it isn't that the overall image is 1,000 nits (or 4,000 or 10,000) that would be uncomfortable, it's just the specular highlights that deliver that peak brightness. So if you think of sunlight reflecting off the chrome on that Harley Davidson you mentioned, that's where the 1,000 nits of peak brightness is, in that small area not in the overall image. The result is a picture that is far more realistic but isn't uncomfortable or damaging to watch.
 
Thanks for that Steve. I remember in my youth that an S-video signal was made up of luminance and chroma (colour). A signal with just luminance is just varying shades of grey from black to white, so I can understand how deciding how to compress chroma information is quite important.

Regarding highlights in HDR, if that's how the bright part of HDR is being used, I can see that as 'safe'. I guess you've seen plenty of UHD HDR footage now to have a good appreciation of how directors/cameramen/colourists are using it.

Do excuse any scepticism I have on this technology. I'm used to stuff going wrong! Let's face it, even trying to get HDR data to a display was a mission not so long ago.
 
Thanks for that Steve. I remember in my youth that an S-video signal was made up of luminance and chroma (colour). A signal with just luminance is just varying shades of grey from black to white, so I can understand how deciding how to compress chroma information is quite important. Regarding highlights in HDR, if that's how the bright part of HDR is being used, I can see that as 'safe'. I guess you've seen plenty of UHD HDR footage now to have a good appreciation of how directors/cameramen/colourists are using it. Do excuse any scepticism I have on this technology. I'm used to stuff going wrong! Let's face it, even trying to get HDR data to a display was a mission not so long ago.
That's OK, it's a common misconception about HDR. What it's about is increasing the dynamic range between the darkest shadows and the peak highlights to give images a greater sense of reality and to retain more detail in the darkest and brightest portions of the image. When done properly it can make a big difference to your viewing experience and it gives greater creative freedom to filmmakers.
 
Hi Steve. Sorry, no misconception of what HDR is and does; the worry was more about content creation, how HDR is being used, or more to the point abused. We've got a small sample of HDR content right now so I'm sure everyone is being very careful. I'm sure in the past you've seen some dreadful DVD or blu-ray content where standards just went straight out of the window. But now with HDR, especially with CGI, I'm sure it would be possible to create some horrific footage.

I'll try and keep optimistic though and from your recent reports and from the podcast, things certainly seem pretty exciting. I don't want to see HDR just yet though, I'll want it too much I'm sure, and there's just too much month at the end of the money right now!
 
Hi Steve. Sorry, no misconception of what HDR is and does; the worry was more about content creation, how HDR is being used, or more to the point abused. We've got a small sample of HDR content right now so I'm sure everyone is being very careful. I'm sure in the past you've seen some dreadful DVD or blu-ray content where standards just went straight out of the window. But now with HDR, especially with CGI, I'm sure it would be possible to create some horrific footage.

I'll try and keep optimistic though and from your recent reports and from the podcast, things certainly seem pretty exciting. I don't want to see HDR just yet though, I'll want it too much I'm sure, and there's just too much month at the end of the money right now!
Go on, have a quick look. What's the worst that can happen...
 
I end up with a shed load of debt. Yes I've got ample 0% plastic to spank, but it all needs paying back!
 
Wow! That's good expert information. Thanks a lot for opening my eyes... and giving me a new problem.

Now, every time I receive a TV offer, I comb the internet looking for the color gamut coverage of the model... And there is the problem.

As far as I know TV manufacturers are not obligated to facilitate this figures for CG Coverage, and they don't. As usual they prefer to hide themselves behind great sounding techo-bable that means nothing like "ColorPrime Pro", "ULTRA Luminance" or "UHD Mastering Engine".

So my question is. Is there a place where you can check out color gamut coverage for any tv model? Any significant database?

If not... there is a good suggestion for a new db site ;)
 
I know here you do provide it, but you don't have reviews for all tv models... hence the question ;)

Thanks for the quick response and the great site (bookmarked and first reference from now on)...
 
@Steve
I know here you do provide it, but you don't have reviews for all tv models... hence the question ;)

Thanks for the quick response and the great site (bookmarked and first reference from now on)...

If the review is not on this site or hdtvtest, I suggest you hold on from buying that TV :)
 
If you take a look at our TV reviews you'll see that they have "How Future Proof is your TV?" box which shows the colour space as a percentage of Rec. 2020. Here's an example – LG B6 (OLED55B6V) UHD 4K TV Review

Hi Steve
Hope you are well
Read an article yesterday stating that Samsung could bring uhd TV with 98 percent of rec2020 by next year (versus 77 percent roughly now)
Do you think it is possible and do we have enough content for that.
 
Hi Steve
Hope you are well
Read an article yesterday stating that Samsung could bring uhd TV with 98 percent of rec2020 by next year (versus 77 percent roughly now)
Do you think it is possible and do we have enough content for that.
Anything is possible but that seems like a big jump in one year. However a panel that can deliver 98% of Rec. 2020 is certainly their ultimate goal.
 
Can Steve or any other person in the know explain to me how content mastered in BT2020 is converted when shown on a display which only supports Rec709. Does it clip the content which falls outside the range or map it all or some combination. If mapping/scaling is involved won't the colours look more muted than content mastered to Rec709 shown on a non WCG display ?
 
Hi, I've got a doubt that I've trying to solve but I cannot find the answer. Does anyone know what is the Colour Gamut of UHD (no HDR) content in Amazon and Netflix? Is it graded for Rec.709 or for Rec.2020? Where can I get that information? Finally, where can I find material graded for WCG? Thanks!
 
What would be great is a list (editable) that details the models of TV's that are WCG.
 
Excuse my bad English.

I don't agree with the chapter over HDR. Many people look at their tv in the evening in a relative dark room. If your set then your tv at more than 150 nits, you must have sun glases. I have a Panasonic OLED tv. If you adjust the brightness of the tv at a confortable level on an HLG signal in a normal dark room, then the tv is able to display the whole 64 to 960 10 bit range, even the 0-1023 range, thus more than the full dynamic off a 0 to 10000 nits HLG signal without any clipping of the highlights. The visual impact will even be greather than looking at the same clip on a future 10000 nits certified monitor in day light because we are many times more sensitive to dynamic in a dark than in a bright environnement. As a conclusion, high nits capable tv's are in the most cases not needed for a common house use. Furthermore, I fin that almost all the HDR/HLG movies that I have seen are very very bad graded with irreal colors and highlights. If such a colorist issue persist, HDR will not be adopted by the end users and HDR will go to a fiasco like 3D. At the moment, the biggest advantage of HDR is that you can shoot more dynamic with you camcoder to avoid over exposure like shooting in raw with a still camera.
 
Welcome to AVF :smashin:
 

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