How much color do displays really need? Part 4: Content Delivery

In the previous post in this series, I made the case for displays with hybrid, custom color gamuts as a great way to deliver coverage of Pointer’s gamut as well as the most important broadcast standards. We can build the hardware today to support these large color gamuts so its seems like a great solution but there is a catch: nobody is broadcasting or distributing these large color gamuts today. So, are we going to have to wait for broadcasters and content creators to slowly catchup, much like we did with HDTV?

What content delivery looks like today

Content is captured and viewed in a wide variety of gamuts across a range of different devices but only broadcast in one gamut.

Content is captured and viewed in a wide variety of gamuts across a range of different devices but only broadcast in one gamut.

Today, content creators are actually shooting in a wide variety of color spaces ranging from RAW to rec.709 to Adobe 1998. They are then forced to cram all of these different sources into the lowest common denominator rec.709 standard for broadcast or distribution. That same content is then displayed on devices with a range of different gamut capabilities from tablets that only cover about 70% of rec.709 to HDTVs that do meet the spec to OLED devices that oversaturate the content.

There’s a lot of diversity on both the capture and display sides and a clear bottleneck in the middle in the form of broadcast and distribution channels.

Adhering to broadcast standards is no longer sufficient to guarantee a good experience for consumers because there’s already too much diversity on the display side alone to rely on one standard. You just can’t be sure that consumers are actually looking at your content on a rec.709-capable device. We’re also losing a lot of the value that creators are capturing and could, in many cases, be delivered to end viewers who have the devices to show it.

How do we get around broadcast standards?

What content delivery looks like tomorrow

The first thing to note is that the internet is democratizing broadcast and distribution channels. With the web we can deliver whatever we want, whenever we want. Some players in the industry, notably Sony, are already doing this with 4K content. If there’s no content available and you believe in 4K resolution, you just deliver your own content directly to your customers.

Wide color gamut displays combined with good quality color management and the web as a broadcast platform will allow content to accurately be displayed in the correct color gamut.

Wide color gamut displays combined with good color management and the web as a broadcast platform will allow content to accurately be displayed in the original color gamut.

Still, this leaves us with some potential experience problems. If the right display gamut is not matched to the right content the results will be no different and that’s why color management is key. There are several companies working on color management solutions and certification programs for devices that will make it possible for wide color gamut displays to handle a variety of incoming gamuts. Using metadata, for example, a wide color gamut display can be alerted to the presence of Adobe RGB content and then remap that content on the fly to assure that it is displayed accurately on that specific panel.

With great color management, we can maximize the gamut on the display side and pull through the best possible gamut for the device we are looking at. In this way, we can deliver always accurate content that meets the designers intent, wether artistic or commercial.

Google claims new Nexus 7 delivers 30% wider range of colors – what do they mean?

Google announced an updated version of their Nexus 7 tablet this morning. Central to Google’s pitch was the improved display with both more pixels and more color. The device does feature an impressively high resolution, packing 2.3 million pixels into a 7″ form factor. But, I’m more interested in the color performance and, on this point, Google was vague offering only that the display, “has a 30% wider range of colors.”

What do they mean by that?

It depends on their frame of reference- what color space they are using and what color gamut standard they are comparing against. Since Google talked about the accuracy of HD video at their event, let’s assume that they are referring to the HDTV broadcast standard (rec.709) and using the common CIE 1976 (u’ v’) color space.

When I measured last year’s Nexus 7, I found it could only reproduce about 82%* of the colors found in the rec.709 standard. Color reproduction was not accurate and a little bit undersaturated on this device:

Color gamut of Google's Nexus 7 versus the HDTV broadcast standard (rec.709). Plotted in CIE 1976 (u' v').

Color gamut of Google’s previous generation Nexus 7 versus the HDTV broadcast standard (rec.709). Plotted in CIE 1976 (u’ v’).

With just a simple calculation, increasing 82% by 30%, you’d get about 106% coverage of the HDTV broadcast standard. While that’s actually a slightly wider color gamut than the standard, it is not uncommon for device makers to use a wider color gamut in order to guarantee the color spec across all devices with some room for manufacturing tolerances. This means video and web content should be displayed accurately and it could make for a great looking display.

We’ll order and measure one as soon as they are available to verify so stay tuned…

* note: I always measure coverage of broadcast standards, not simply total area since that can be misleading. However, in this case, coverage and area are nearly the same since the Nexus 7′s gamut is smaller than rec.709.

How much color gamut do displays really need? Part 3: Existing color gamut standards

Last week I looked at the three “P’s” of human color perception– physical, physiological and psychological– as a way to help define a color gamut for the ideal display. Based on real world examples from art and commerce, I concluded that the range of colors found in nature, as measured by Pointer, provided the best fit with our two design goals which were an accurate and exciting, immersive experience.

This week, I’d like to get a little more practical and take a look at existing color gamut standards to see what we might realistically be able to achieve today.

What fits best?

Color gamut of 4,000 surface colors found in nature as measured by Pointer in 1980 against the color gamut of the iPhone 5.

Color gamut of 4,000 surface colors found in nature as measured by Pointer in 1980 against the color gamut of the iPhone 5.

The first thing you’ll notice about Pointer’s gamut (pictured above again) is that it’s a pretty odd, squiggly shape. This means it is going to be difficult to cover efficiently with a three primary system that mixes just red, green and blue to create all the colors we see, like the LCD found in the iPhone. In order to cover Pointer’s with just those three colors, we’d need to make them extremely saturated. There are proposed standards that take this  approach, such as rec.2020, but since they are not practical to implement today from a technology standpoint I’ve decided to ignore them for this discussion.

For the near future, we’ll need to rely on just three colors to get the job done, so what can we do now? Let’s look at two popular wide color gamut standards: Adobe 1998 and DCI-P3:

Current wide color gamut standards Adobe RGB 1998, commonly used by pro photographers and designers, and DCI-P3, used in digital cinema, compared to Pointer's gamut in CIE 1976

Current wide color gamut standards Adobe RGB 1998, commonly used by pro photographers and designers, and DCI-P3, used in digital cinema, compared to Pointer’s gamut in CIE 1976

Let’s start with Adobe 1998. Many people are familiar with this color gamut since it is found as an option on many consumer cameras and it is popular among creative professionals. It certainly covers a significantly wider range of colors than the HDTV broadcast standard with a very deep green point. The rich cyans that we talked about in the movie “The Ring” would look great in Adobe 1998. But, we’re not getting any more of those exciting reds and oranges. In fact, Adobe’s red point is identical to the HDTV broadcast standard.

What about DCI-P3 then? Designed to match the color gamut of color film and used in cinemas all over the world, DCI-P3 has a very wide gamut. The reds are particularly deep and, of course, all of the colors from the movies we looked at are covered. Still, it’s missing a lot of the deep greens found in Adobe 1998 and only just fits the green Pantone color of the year. So DCI-P3 is not quite perfect either.

What about a hybrid, custom gamut? 

What if we combined the green from Adobe with the red from DCI-P3 and their shared blue point? We’d end up with pretty good, high 90’s percentage coverage of Pointer’s gamut, coverage of all of the existing HDTV broadcast content, full coverage of cinema content from Hollywood and a superior ecommerce experience with most of the colors from the natural world covered.

Hybrid color gamut standard that combines the green point from Adobe 1998 with the deep red of DCI-P3

Hybrid color gamut standard that combines the green point from Adobe 1998 with the deep red of DCI-P3

Looks pretty great and we can make displays now that cover this color gamut with today’s technology. But how would it work on the content side? Would we need to get together and agree on this new standard and then wait for years while it is slowly adopted by content creators and display makers?

Next week

Next week we’ll look at how content delivery might evolve to support gamuts like this without the need for major changes to broadcast standards.

ITU agrees on HEVC h.265 codec

h-265-logo,Q-D-349573-3The ITU announced today that it’s members have agreed upon a new high efficiency video codec. Dubbed HEVC H.265, the new format is designed to improve on and ultimately replace the current king of all codecs, H.264/MPEG-4 AVC which covers 80% of internet video today.

So far, a lot of attention has been given to the codec’s ability to deliver the same quality video as 264 with only half the bandwidth. That kind of efficiency improvement is a big deal– it could reduce strain on networks and bring high-resolution 4K content delivery over the internet closer to reality.

h265 vs h264 quality comparisonThere are also some important changes for color in the new spec. Recent drafts by the ITU’s Joint Collaborative Team on Video Coding (JCT-VC) have added support for wider color gamuts like Adobe RGB 1998 and 12-bit video. This paves the way for fantastic looking color as wide gamut-capable hardware starts to become more widely available.

Can your TV accurately display your favorite NFL team’s colors?

Over the weekend I saw this interesting tweet about color gamut and the NFL and I had to find out if it was true:

Could it be that something as simple as an NFL jersey is not within the color gamut of modern HDTVs? I mapped the Broncos team colors onto the CIE 1976 color space along with the HDTV color gamut standard, called rec.709. As you can see, the orange is right on the edge and the blue is indeed outside the gamut.

When we think of high color content, we think of action movies and video games, but this exemplifies how color performance affects everything we see on our TVs, even down to the jersey being worn by our favorite sports team. Luckily high color displays are on their way to fix this problem.  As you can see, the Bronco’s colors fall nicely within the much wider DCI-P3 color gamut.