Color IQ

As I mentioned earlier, the technology at the heart of the Philips 276E6 monitor is QD Vision's Color IQ quantum dot technology. To gain a better understanding of how this differs from other quantum dot implementations currently used in the market, I spoke with QD Vision's Chief Marketing Officer John Volkmann.

Quantum dots are a type of semiconducting nanocrystal. They're typically made of cadmium selenide or indium phosphide, and when used in displays they have a diameter less than ten nanometers. What makes them interesting is that they exhibit a property known as photoluminescence, which means that they emit light after absorbing photons.

In LCD displays this property is highly desirable, as it means that you're able to place an array of quantum dots between the backlight and the color filters to reduce the frequency of the light emitted by the blue backlighting. By altering the diameter of the quantum dots you can control the frequency and wavelength of the light that is emitted, which allows for the emission of specific red, blue, and green wavelengths at the required intensity to cover your target color gamut. Smaller quantum dots on the scale of one or two nanometers emit wavelengths of light in the blue part of the visible spectrum, while larger quantum dots with a diameter of six or seven nanometers emit red light.

A question you may have is why this is actually necessary. I mentioned above that quantum dots are typically used to convert blue light into red and green light, and the use of blue LEDs for backlighting is not unique to quantum dot displays. Almost all modern LCD displays use LED backlighting, and the majority of them use what is commonly referred to as WLED backlighting. In truth, these "white" LEDs are really blue LEDs paired with a yellow phosphor, and through this process wavelengths of blue, green, and red light are produced. Unfortunately, there is still a very significant blue bias in the final output, and the intensity of the desired red and green wavelengths is relatively low. Because of this, these displays are limited in the range of green and red colors they can reproduce, and to date most monitors of this type have been limited to roughly 99% of the sRGB color gamut.

To produce a wider color gamut with LED backlights alone, vendors have employed the use of different technologies. The most prominent is GB-r backlighting, which pairs green and blue LEDs with a red phosphor to allow for green and red light of a greater intensity. Unfortunately, such designs have shown to be quite expensive, and this has kept wide gamut displays priced well outside what is affordable for the average consumer. An even smaller group of displays has employed full RGB backlighting, but due to cost this did not see much adoption by any display vendor.

The cost-related issues of RGB and GB-r backlighting is the problem that QD Vision hopes to solve with their Color IQ technology. Color IQ's appeal is that it works with standard edge-lit displays, and it takes advantage of the blue LED backlighting that those displays employ. Most quantum dot technologies require the use of expensive full-array backlighting because they use a thin film layer with quantum dots embedded throughout it which sits between the backlighting array and the color filter layer. In contrast, Color IQ uses small glass cylinders that sit in front of the blue LEDs at the edge of the display. According to QD Vision, the cost of a film-based solution for a display around the size of a 50" television can cost around $100, while their quantum dot solution for edge-lit displays will only cost around $20.

With QD Vision's current technology the cylinders with quantum dots sit between the blue LEDs and the light guide plate that distributes the light across the panel. With such an implementation one can expect displays that closely cover the Adobe RGB and DCI-P3 color gamuts depending on exactly how the quantum dots are tuned. According to QD Vision, quantum dot technologies perform best when the quantum dot array is as close to the backlight as possible. Within the next few years they hope to be able to deliver a "chiplet" solution, which consists of a quantum dot matrix mounted in a bead of glass right atop the LEDs. Moving beyond that will be integrating the quantum dot matrix right into the LEDs themselves. Right now such solutions are infeasible due to heat degradation, but they will be necessary as we move toward full coverage of the Rec. 2020 color gamut.

Philips 276E6: The First Color IQ Desktop Monitor Contrast, Brightness, and Gamut
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  • Guspaz - Friday, April 29, 2016 - link

    The U2711 was a high-end monitor, and so one of the advertised features was that Dell individually calibrated every monitor at the factory. They included with each monitor a custom calibration report that had the deltaE and such things, with graphs and whatnot. Dell provided a generic ICC profile file for the monitor, so I would imagine that the monitor itself was calibrated so that the ICC profile would match the physical monitor.

    If I pick option 2 (monitor set to sRGB, Windows set to ICC profile), then how does Windows know that the monitor is expecting the input to be in the sRGB colour space?
    Reply
  • Brandon Chester - Friday, April 29, 2016 - link

    To the best of my knowledge Dell's factory calibration is at the internal LUT level so you can plug it into any device and have it be accurate (the best type of calibration). The ICC is probably just something generic and I doubt it contains a VCGT for the GPU.

    I would choose "option 4", which is to say, just leave the OS color management alone because Dell has been playing this game long enough to know that the Windows CMM doesn't work, has made your monitor usable in sRGB without having to mess with it, and given you the option to turn on Adobe RGB when you open Lightroom or some other program.
    Reply
  • jlabelle2 - Wednesday, May 4, 2016 - link

    - If I pick option 2 (monitor set to sRGB, Windows set to ICC profile), then how does Windows know that the monitor is expecting the input to be in the sRGB colour space? -

    Option 2 is Option 4 with a display ICC calibration. If you are using a color managed application, it reads embedded profile and therefore will display correctly. On most of the case where it is not color managed (wall paper, Edge, modern Windows app...), the assumption is that you would use sRGB content anyway (web, pictures you received..).
    The ICC display profile ensure that you are correcting the latest inaccuracy from the Dell screen compared to sRGB color space (as, even out of the box, calibrated by Dell, it is not perfect).

    If you have no calibration probe, your best bet is option 4.
    Reply
  • jlabelle - Friday, April 29, 2016 - link

    - On my Mac I just set the ICC profile and everything works immediately and perfectly. -

    For record, it does because ...it does not really take advantage of the wide gamut in your case !
    Reply
  • Spunjji - Thursday, April 28, 2016 - link

    "for photographers and other professionals... the relatively low resolution poses less of a problem"

    Higher pixel density is actually huge asset - you can get a better idea of critical image sharpness without zooming in, and getting above 1080p is a massive help for getting more working area between all the toolbars.

    So really, having wide gamut /and/ high pixel density would be great. Hopefully they get on that! :)
    Reply
  • Brandon Chester - Thursday, April 28, 2016 - link

    I definitely agree. Anyone who has done photo editing on a 4K or 5K display can attest to the improvement. I just meant that relative to someone who writes word documents all day, the lower resolution is probably less of an issue. Reply
  • Spunjji - Thursday, April 28, 2016 - link

    If I could edit, I'd add thanks for the article - it was a fascinating read and I was certainly not aware that Apple had such a commanding lead in colour calibration support. Food for thought. Reply
  • jlabelle - Friday, April 29, 2016 - link

    - I was certainly not aware that Apple had such a commanding lead in colour calibration support. Food for thought.-

    Let's be honest, having a less confusing way of setting once your display ICC profile (which anyway is done automatically by the software coming with your calibration probe) is NOT having a commanding lead in color calibration support. That is a silly statement.
    Reply
  • willis936 - Thursday, April 28, 2016 - link

    I'm seeing a lot of gripes about windows color management. Doesn't argyllcms take care of that? Anyone shelling out for wide gamut should also spend the $50 for a cheap colorimeter. Reply
  • Brandon Chester - Thursday, April 28, 2016 - link

    1. Cheap colorimeters are so inaccurate that they're basically useless.

    2. Argyll doesn't solve any of the problems. You need your OS, its frameworks, and its applications to all understand color management and work with the CMM. ArgyllCMS is basically a tool for profiling and creating ICC profiles, it can't make software understand and utilize them.
    Reply

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