Constraining To sRGB

Every monitor and television has an internal lookup table, which is independent of the LUT used by the GPU in the connected device. This is essentially a stored list of calculations that define what output value should be displayed on the monitor for a given input value from a computer or set top box. This may or may not be user accessible, and high end monitors will have a high precision internal lookup table which is really more like a 3D cube that can be used to adjust intermediate points of gradation where colors are blended instead of simply adjusting three individual tables for each primary color. While that is beyond the scope of this article, the concept of a monitor's LUT is important to the topic of monitor display modes. Wide gamut monitors almost always have an sRGB display mode which constrains the display to the sRGB gamut, and this is accomplished at the level of the display's LUT with no connection to the OS or to a GPU's LUT. 

With the previous section discussing how ICC profiles are used to make the OS and its applications aware of a monitor's native color space, you may be wondering what the point of offering a narrower gamut display mode is. Before moving on, I need to cover one other point about color management.

The function that performs the transforms between different color spaces is called the color management module, or CMM for short. If one wants to think of color management as a stack or a chain, you have color descriptions in ICC profiles on top, with the CMM sitting in the middle, and your color management API on the bottom for programs to access. When content that is not made in the display's native color space is encountered, the color management module first looks at the data provided about the content's color characteristics. It then transforms these values into an intermediate color space based on the CIE 1931 color space, which encompasses all colors that can be seen by the human eye. This is called the profile connection space, or the PCS. From the PCS, the values are then mapped into the target color space of the display, and in theory this should provide an "accurate" representation.

In the case of moving from a smaller gamut to one that is a superset of it, the content should look identical to a reference display for the content's native color space, as the larger gamut is perfectly capable of showing all the colors that exist in the smaller one, with those colors simply being defined by different coordinates. When moving from a larger gamut to a smaller one there needs to be a decision made about how to represent colors that can't even be shown in the target space. Typically, the solution has been to scale all colors appropriately to maintain the relative difference between colors, which means that the image is technically less saturated in areas where it could have been rendered natively, which is a tradeoff to properly maintain gradations within an image.

Unfortunately, the fact of the matter is that not all applications will play nice with OS level color management, particularly on Windows. In these situations, the system's color management module is never invoked, and no color management occurs at all. The typical result is that content is presented as though it was native to the monitor's color space, resulting in significant oversaturation and a completely inaccurate image. Because Windows is the most widely used operating system for computers, monitor manufacturers have gotten around the deficiencies of the system's color management by simply allowing users to use an sRGB mode that constrains the display's gamut at the level of the monitor LUT. This means that you lose any benefits of the wide gamut mode, but because most content is sRGB there's typically no difference, and when you do need to use a wide gamut for photo editing or other work you can toggle it back on temporarily.

The included sRGB option does not alter the output in any manner

On the Philips 276E6, there is unfortunately no hardware-based solution to the color management problem provided. The issue is that there is no working sRGB display mode. In fact, the original unit I received had no sRGB mode at all, which I found quite surprising. After emailing QD Vision who then communicated with Philips, I was shipped a replacement unit that was apparently from a later production run where an sRGB mode was added. Upon setting it up I was delighted to see that there was an sRGB toggle in the settings menu, but this quickly faded as I realized that the setting did absolutely nothing, and I confirmed that by measuring the display in both the Adobe RGB mode and the sRGB mode.

To not have an sRGB mode is one problem, but to have the option and have it not even do anything is arguably much worse, as it's like advertising a feature that doesn't work rather than not offering it. With no way to constrain the gamut at the hardware level, the only solution is to use ICC profile and rely on applications being color managed. At this point another problem crops up, which is that the Philips 276E6 doesn't provide an ICC profile that properly characterizes its output, and so there's no way for applications to properly display images even if they do support color management.

To fix the situation somewhat, you need to go back to the Windows Color Management settings, ensure that you've enabled calibration using the confusing steps that I described earlier, and finally set your device profile to the Adobe RGB (1998) profile in the drop down menu. If that profile isn't there by default, it's readily available on the internet and can be installed after downloading by right clicking and installing from the context menu.

Technically it's improper to use the standard Adobe RGB profile as the device profile, as the monitor is not perfectly matched to the Adobe RGB spec which is pretty clear based on our measurement results from earlier. However, it's the best solution there is when a proper ICC isn't provided, apart from using a $1500 spectrophotometer to make your own ICC which defeats the entire point of the 276E6's low price. It's worth noting that in my case I've set the device profile to Adobe RGB system wide, because I've been testing the Philips 276E6 on its own. For users with multiple displays this should be set for each display individually in the original settings screen depending on what gamut each one supports. At this point applications that support color management will render images more correctly, but applications being properly color managed is not a given.

At both the OS level and the application level, there are programs that just don't play nice with color management. Above you can see an example of how the new Windows Photos app actually isn't displaying an image correctly, while the very old Windows Photo Viewer actually does, with Photoshop also there as a reference application that is known to support color management. One thing to note is that if you grab the images I've used off the web they'll actually look more like the improperly managed applications in these screenshots. This is due to the color transformations that I described earlier, with me explicitly choosing to target the sRGB color space in these screenshots grabbed from an Adobe RGB display, which reduces the saturation of colors to maintain gradations. I think the surrounding discussion makes it fairly obvious why I'm not relying on the proper rendition of Adobe RGB tagged images to demonstrate this, and since the relative difference between colors is maintained it doesn't have any impact on the comparison.

These issues extend to other parts of Windows as well, including areas such as the wallpaper. When the core image applications of an operating system aren't managing color properly, especially such basic things like the desktop wallpaper, it's difficult to imagine that third party software is either.

Probably the best example I can find of an application that is only somewhat color managed is Google Chrome. Web browsers in general have had a lot of problems with color management. Microsoft Edge, which is Microsoft's brand new browser, doesn't support it at all. Firefox requires configuration modifications to work with anything beyond tagged images. In the case of Chrome, there is support for displaying images with embedded ICC profiles. Unfortunately, this really doesn't go far enough to address all possible cases, and this is a recurring problem that I've found. While being able to properly display images that are tagged is a good thing, many programs will simply assume that an image was made for the target device's color space if they are not tagged at all. You can see the problems this causes in the image above, with an image grabbed right from the internet displaying incorrectly in Chrome because it has no embedded sRGB profile. In my experience this is often the case, as you usually need to use a program like Photoshop and explicitly include an ICC profile to have a tagged image.

In almost all cases, the assumption that content is designed with the target device's color characteristics in mind is an incorrect assumption to make, as all content made for the web targets the sRGB standard. Safari is, to my knowledge, the only major web browser that adopts this behavior and assumes that untagged images are sRGB. The same is true for the display of CSS colors. Although they are explicitly defined as being in the sRGB color space by the CSS color specification, with no profile information it's the job of the web browser to do the work there, and most simply don't bother. As a result, you don't see a website as the designer intended it to be, and the colors can be quite straining to look at in some cases. AnandTech itself is a good example, with some of the blue text being much more difficult to read when the saturation is ramped up, and the orange highlights becoming particularly gaudy looking.

In the end there's just too much unreliability on Windows within the operating system, Microsoft's own apps, and third party apps to simply rely on the color management system to make sure everything displays correctly. Windows is by far the most used operating system for consumer desktop computers and laptops, and Philips really should have included a proper sRGB mode on the 276E6 so users would be able to see most content properly, with Adobe RGB being available when working in applications that actually require and support it. While the core issue is something that Microsoft seriously needs to address, right now the solution is for monitor manufacturers to fill in the gaps, and companies that are entering this space using QD Vision's technology really need to make note of this.

Color Management And ICC Profiles Final Words
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  • Brandon Chester - Thursday, April 28, 2016 - link

    Ryan was up very late doing some editing and must have made it when he expanded on my admittedly sparce placeholder title (Monitor Review). My apologies.
  • Infy2 - Thursday, April 28, 2016 - link

    The message of this article is for average Windows user to stay away from wide gamut monitors.
  • Murloc - Thursday, April 28, 2016 - link

    average user thinks oversaturation looks cool
  • watersb - Thursday, April 28, 2016 - link

    Excellent. Thanks for this in-depth discussion. I know very little about color and color management.

    Yesterday, I was in an Apple Store and I compared wide-gamut images side by side on the new, 9.7-inch iPad Pro, the 12-inch one, and the 5K iMac. I used iconFactory's blog post for reference images. Wow.

    This is becoming a real thing for popular consumer devices. Interesting times!
  • theduckofdeath - Thursday, April 28, 2016 - link

    The only thing I'm getting from this review is, I have a strong feeling that markets with stronger marketing regulations will soon nerf the Quantum Dot term the same way "LED" displays were a few years ago. The marketing implies that QD is as advanced as OLED while the displays clearly still use edge lighting with all of its issues.
  • saratoga4 - Thursday, April 28, 2016 - link

    The marketing on hype on QD is particularly ridiculous given that they're essentially a cost-reduction measure designed to save a few dollars on multi-color LEDs or OLED while (hopefully) being good enough.
  • Murloc - Thursday, April 28, 2016 - link

    80$ is not a few.
    A new thing or a cost reduction are the same thing in this case: consumers will have something they didn't have before.
  • saratoga4 - Thursday, April 28, 2016 - link

    Going from 1 type of LED to 2 types of LED in an array doesn't anywhere near $80. The savings is much larger compared to OLED, but OLED has other advantages beyond gamut that QDs can't match anyway.
  • name99 - Thursday, April 28, 2016 - link

    I think you're missing the larger picture.
    Of course any technology can be cost-cut to the point where it is a joke, and Phillips seem to have done that here. OK, Phillips being stupid, nothing new there. But that's not interesting.

    The more interesting aspect is that we are moving towards richer monitor technology. It started with retina (sorry HiDPI !) displays, now we're going to wider gamut. At some point wider gamut is going to move to something like 16 bits per pixel rather than 8 (or occasionally 10 or 12), along with maybe even 4 phosphors. And at some point the standard device frame rate is going to up to 120fps.

    OK, so with this hardware background, it's now interesting to contemplate the SW background.
    In one corner we have MS. Apparently still incapable of handling color correction after all these years, and incapable of handling the UI. Ad that to their HiDPI support. They seem unlikely to adapt well to this new world...

    In the second corner we have Android. Not clear to me how much better off they are. They have handled DPI a lot better, which is a good start. As far as I know there is still no color correction built into Android; but the larger issue is one of how easily their architecture would allow for inserting color correction. Can they do it in such a way that all (or at least most) apps just do the right thing? And would it rely on the phone OEMs to create drivers and lookup tables that most of them would screw up?

    In the third corner we have Apple which seems perfectly positioned for all this (meaning that they will likely drive it). They've been happy to push hiDPI (including on OSX as fast as Intel's built-in GPU's allows it ---which wasn't very fast, suggesting that maybe they'd be better off with another vendor for OSX SoCs, but that's a different issue), and they're now pushing color accuracy both on the camera side (TrueTone flash, high dynamic range sensors) and the screen side (new iPad Pro screen, presumably to spread throughout the product line as manufacturing volumes and power budgets allow).
    I fully expect them to stay on this path for a while, never actually stating technical phrases like "full Adobe RGB Gamut" but constantly subtly pointing out in their keynotes and advertising "Our colors look good, and look correct, across ALL our devices --- photos on your iPhone look exactly the same on your iMac. Good luck getting that consistency with photo from your Android phone on your Windows screen."

    From this point of view, then, the relevance and interest of QD technology is whether it allows larger gamut to move to iPhone this year or at least soon.
  • jlabelle - Friday, April 29, 2016 - link

    - Apparently still incapable of handling color correction after all these years, and incapable of handling the UI. Ad that to their HiDPI support. They seem unlikely to adapt well to this new world... -

    such statement is not correct and the article describes it pretty clearly. Beyond the way to set it up (which, yes, is somehow confusing), the real issue is simply that many programs are not color managed.
    This is not only limited to Windows and OS X is suffering of the same issue so it has nothing to do with Windows per see but the programs you are using.
    The issue behind is that some default program on Windows are not color managed. It seems it is the issue with Store app (like it is for iOS apps that make iPad useless for photo editing for instance). So some important apps like Photo and Edge do not take care of that. That is a big issue.
    But many programs does.

    That is why there are 3 different cases :
    1/ Use a screen very accurate within sRGB gamut out of the box - only use sRGB images --> no issue anymore but obviously you will never display any image beyond sRGB

    2/ Use a screen with sRGB gamut (or a wide gamut screen that you switch to sRGB mode) with calibrated with an ICC profile set as default (as described) - use only sRGB images --> here, you will have perfect color accuracy for all applications color managed. In case of applications not color managed (Edge, Photo, Chrome...), you will have the color inaccuracy of the screen default (because ICC profile not applied) BUT you will not have images under or over saturated. Therefore, the impact will still be minimal for the user.

    3/ use a wide gamut screen : then, you have no other choice that carefully use color managed application --> for every application color managed, display will be fine and you will take advantage of the wider gamut. For all others, the images will appear oversaturated.

    It is such an issue that I used to have a wide color gamut DELL U2711 screen.
    1/ first, you only have a good accuracy in color managed applications but in others, everything is oversatured.
    2/ Second, while shooting FF DSLR in aRGB, I may have seen less than 10 pictures out of 70 000 where you could see in an direct A-B comparison a tiny difference between the sRGB version and aRGB. In real world, it is VERY unlikely to go beyond sRGB.
    3/ Third, even if you keep for you aRGB versions of your pictures (to take advantage of your screen), you have to have a sRGB copy because when you share it outside, other people will face the issue on non color managed application that your pictures will be completely washed out. And even many online print shop only take sRGB.

    At the end of the day, it is so much a hassle for virtually almost 0 visual benefit (speaking of photo of real color in the nature) that I now have a Dell U2313UH which is a sRGB gamut screen.

    Bottom line : wide gamut screen currently is a chore and NOT recommended. And not only Windows, nowhere because even if your browser is displaying correctly the image (Safari, Firefox with a certain flag activated), what is the point then to have a wide color gamut screen to see sRGB pictures ?

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