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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  • jlabelle - Friday, April 29, 2016 - link

    - 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 -

    If you are speaking of Android, you should compare that in Windows Store with Windows apps from the Store.
    For those, the scaling is just perfect and it is handling ANY screen size / resolution / orientation perfectly.
    Only issue with scaling are Win32 programs not using hidpi API released 9 years ago with Windows 7 (at a time where Android was not a thing).

    - As far as I know there is still no color correction built into Android -

    Android is the worse on this because you have virtually 0 color management.

    bq. In the third corner we have Apple which seems perfectly positioned for all this (meaning that they will likely drive it).

    Again, this is misleading.
    For instance, iOS way of handling color management (see test on the iPad Pro) make the use of wide gamut screen virtually useless (for now) as there are no ways for a developer to take advantage of it. What it seems to do is basically apply a ICC profile to target sRGB color space.
    Scaling is not a question really as resolution are pretty much hard coded but again, Windows app are scaling perfectly.

    OS X has some "native" applications color managed (like Safari) but the same issue occur that the program needs to be color managed otherwise you have the same issue.
    For scaling, this is exactly like Windows with hidpi API existing like forever and developer just need to use it. Maybe there are more application which are using it. But that's it.
    OS X does not have really (from an OS point of view) an inherent advantage compared to Windows on color management / hiDPI screen.

    bq. they're now pushing color accuracy both on the camera side (TrueTone flash, high dynamic range sensors)

    actually, Apple is using 1/3" camera sensor, one of the smaller size in the industry (or only found in low end phone like Lumia 640XL...) and therefore the dynamic range is more limited than the competition (because it is mainly directly link to sensor size).

    - and the screen side -
    nothing exclusive to Apple. For instance, speaking of Windows here and therefore the Surface or the Lumia 950, they both have more color accurate screen that all the various iPad and the iPhone (albeit all are VERY good in color accuracy).

    bq. "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."

    It is no luck. Just pick the right product. If you pick a Surface and a Lumia 950 for instance, you will have the same great experience. And using a Samsung S6-S7 or accurate Android phone will give you the same.

    Seems indeed that advertising is working correctly for people to believe that Apple has inherent advantage here.

    - the relevance and interest of QD technology is whether it allows larger gamut to move to iPhone this year or at least soon.

    Until developer can take advantage of it, it has not advantage for end user. So as good is the color gamut of the iPad Pro, it is useless from an end user point of view.
  • Brandon Chester - Friday, April 29, 2016 - link

    I've already addressed why your understanding of the situation on the iPad is incorrect in my article specifically about it. Please do not spread serious misinformation in the comments or I will have to remove them; this is already an issue that is confusing to many people.
  • theduckofdeath - Friday, April 29, 2016 - link

    I don't get what bigger picture I'm missing here. Yes, LCD tech has evolved a lot over the years. But, it's just the faux marketing these manufacturers always stoop to, to give the impression that they're selling something better than LCD. A few years ago it was LED now it's Quantum Dots. Both insinuating that the backlight isn't the usual old flawed edge lit design.
  • alphasquadron - Thursday, April 28, 2016 - link

    As a Windows User(not by choice but because it supports a lot of software and games), it is tiring to see the slow pace at which Windows fixes problems. When are they going to get 4k scaling done correctly. And I remember when I got my new computer and going through the same confusing ICC sub-menus to get the actual settings.

    Also what was Phillips or QD Vision thinking when they sent a reviewer of tech site that is testing their monitor for color accuracy a fake sRGB mode. I mean he just mentioned that there was no sRGB mode on the monitor so what do you think the first thing he is going to test when he gets the new monitor is. I'm still confused whether the mode actually did change something or if they are just that dumb(or they think reviewers are that dumb).
  • Murloc - Thursday, April 28, 2016 - link

    maybe they messed up while doing a quick fix. I hope.
  • Brandon Chester - Thursday, April 28, 2016 - link

    For the record, I spent a long time trying to prove to myself that it did do something. Unfortunately, if it truly were constraining the gamut it would be so completely obvious upon toggling it that you wouldn't even need to make measurements. I did measure anyway, and it truly didn't change the output at all.
  • Guspaz - Thursday, April 28, 2016 - link

    All this talk of colour management... It all works so easily on my macbook (load the profile Anand made, and everything looks correct), but on my main PC, it's a mess...

    I've got a Dell U2711 running Windows 10. That's a wide-gamut display, and I do have an ICC profile for it. The display was also factory-calibrated (it shipped with a printed report on the results).

    If I want the most trouble-free setup where most stuff looks correct, which of these is the correct approach:

    1) Set monitor to default profile and set Windows to ICC profile
    2) Set monitor to sRGB profile and set Windows to ICC profile
    3) Set monitor to default profile and set Windows to sRGB profile
    4) Set monitor to sRGB profile and set Windows to sRGB profile

    I'm guessing option 1 is correct for wide-gamut use, but the crappy Windows colour management would mess everything up. So if I want to just go for sRGB, it seems to me that option 4 is probably correct? Or is option 2 what I want?

    This is all so confusing. On my Mac I just set the ICC profile and everything works immediately and perfectly.
  • Murloc - Thursday, April 28, 2016 - link

    yeah MacOS got this down unlike Windows.

    I wonder how amenable Linux is in this regard.
  • tuxRoller - Thursday, April 28, 2016 - link

    Pretty much as good as Mac, actually.
    Checkout my comments on the recent 9.7" iPad review (the one that dealt with color management).
  • jlabelle - Friday, April 29, 2016 - link

    See my answer in page 2. I was in your EXACT same case.

    1) I guess you have a ICC profile so you are able to calibrate the screen yourself with a probe or you have a generic ICC profile from a DELL review (which means that you do not consider production variation and variatin over time) ?  this is theoretical ideal situation to take advantage of wige gamut screen…except, I do not advise it for the reason describe below.
    2) Hassle free solution : same as above but you constraint yourself with sRGB color space. You will have good color accuracy on color managed application. And even for non color managed application, and even if your ICC profile is not very good, you will have not problem of oversaturation or washed out colors.
    3) make no sense at all ! It means that you are saying that the DELL is perfectly accurate according to sRGB color space and gamut. Obviously, it cannot be further from the truth so you will end up with all your colors (EVEN for color managed applications) oversaturated. No, no, NO !
    4) This is the equivalent as what the article advice for the Philips : you put the screen in sRGB mode. You do not have any ICC display profile (because you do not have the necessary calibration equipement). So you are assuming that it is correctly calibrated and are saying to the OS that you display is perfect according to sRGB. Actually, this is the standard and you do not need to do anything to be in this situation.

    The preferred solution is by far the number 2.

    To understand why, let’s reverse the discussion and ask you (or people) why they think they benefit from a wide gamut screen ?
    • To surf the web ? No because websites are targeting sRGB anyway
    • To view pictures received by email or taken by you ? In most cases, no because mobile phone, compact cameras and even most DSLR are setup to take sRGB pictures
    • To view film ? It is slightly more complicated but anyway, there is no content with wide gamut (to make things simple) and anyway no consumer video software that would manage it. So you would end up with over saturated colors permanently. Except if this is your thing…

    So then, in which case would you have any benefits ?
    IF you have your own DSLR/mirrorless and IF you set it up in aRGB mode and IF you make always duplicates of every single picture in sRGB anyway that you want to share / display on the web / bring or sent to printing.

    And even if all those “IF” are fulfilled, you will end up having over saturated colors in most of your applications, when surfing the web, when watching pictures of others… All that just to be able to see, on your own pictures, maybe a tiny difference with side-by-side comparison in 0,001% of the case (I am not making this number, it is the proportion of pictures where I was able to spot a difference).

    Long story short : a wide gamut screen makes NO sense currently. And there is a reason why it is said that it only make sense for professional for very specific application. And those people do not come here to ask if it makes sense because they are aware of all this.

    Bottom line : choose option 2.

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