6P LASER and the 2020 ideal
Insight Media analyst Chris Chinnock threw a monkey wrench between the spokes of the cutting edge of High-end Hometheater, this past week following his visit of the Barco factory in Belgium, when he posited that 6P cannot meet or exceed the Rec. 2020. To meet this widest colour gamut allowing for the deepest reds, blues and greens, 3P LASER with a separate anti-speckle remedy would be required. The second set of RGB Primary colours, slightly off-set to the base primaries, this makes the Red, Green and Blue less coherent, and the narrow spectrum, and coherence of the LASER light is what causes speckle on the screen.
So, what can be the reasoning behind this. The delta between the two sets of primaries isn’t that large or is it, and if the first set of primaries is right at the frequencies specified in Rec.2020, why not select higher frequencies for the second, off-set primary colours.
So, I asked Chris to clarify his position:
“The 2020 spec requires the RGB primaries be right on the spectral locus – right at the edge of the color horseshoe. To actually meet the spec, you must use lasers at those primaries, which are commercially hard to obtain. With a 6p system, you have 2 red, 2 green and 2 blue lasers offset by 10-20 nm. This essentially brings the resulting color space in off the spectral locus slightly. Technically, that means is it not achieving 100% of the 2020 gamut, but I suspect that are essentially no images where this slight detuning would be visible”.
So, it is indeed the off-set primaries, and it is a formal non-compliance, not a substantial one.
The 2020 standard was set as ideal, as a target beyond reach of even OLED. In LCD flat panels Quantum Dots used to convert blue LED light to red, green and Blue, can only reach 93% of the required colour space, with further research, it may reach up to 97% of the current Rec.2020 colour space, according to public statements by the manufacturer. And the around $120,000 list price 3 DMD 4K LED projector announced by DPI can’t fully meet the requirement either, as Mike Bridwell, the vendor’s VP told me at the ISE show this February, the Red Primary falls a few percentage points short of the standard.
Compared to the issue for flat panels the commercial availability of the LASERS required for high-end projection displays is on a minute scale, but still a serious one, as feature film content production and presentation leads the industry on this.
So, what to do, will we see a revisit of the issue of 100% NTSC colour and available efficient CRT Phosphor. NTSC setting a paper standard requiring a wide colour space that could not be met efficiently by available phosphors, used in CRTs to convert electromagnetic energy to optical energy, or light. In Europe the EBU instead chose a colourspace and associated primary colours amounting to approximately 70 percent of the NTSC standard. To work with efficient and commercially available phosphors. In practice NTSC TVs used the same phosphors and colours, turning the NTSC standard a paper, not a de-facto standard, as it concerns colour.
So, will we see a change to the standard to follow what is possible, and not trying to make work, what to date does not work. Chris expects so:
“I suspect the 2020 spec will be modified as there is momentum building to do so. It would likely adjust the primaries to reflect commercially available lasers and provide a tolerance to the primaries so the 6p system would be fully compliant”.
So, we can savely go ahead and follow through without worrying about a standard not being met. Intense colours will be reproduced.
There will be demo’s with 2020 content on various wide gamut displays, at the Display Summit conference, taking place on June 15-16, in Orlando Florida, ahead of Infocomm. There will also be the Eizo monitor that has an Alert mode to show colours outside Rec. 709 in a greyscale, or clipped to 709 space, to show how it will look on a regular HDTV.