Are More or Smarter Primaries the Solution to Metameric Failure in Laser Projectors?

With laser projectors, three very narrow primaries create a very large color gamut that is very close to the 2020 color gamut. But research has shown that with very narrow primaries, people can perceive a certain color differently – something that does not happen with displays that have spectrally broad primaries used in a Xenon lamp projector and many other displays. This is called metameric failure.

In a very informative tutorial on color science, David Long of the Rochester Institute of Technology (RIT) explained some testing they did using the standard Macbeth color chart. They offered a way to measure the degree of failure, finding the 2020 display with laser primaries would indeed be much worse from a metamerism point of view than a CRT display and DLP projectors.

To show metameric failure is real, Long set-up an experiment that allowed participants to adjust a laser-based display to try to match a series of gray patches shown on a reference monitor. What he found was a wide variety in the adjusted images.

Long then analyzed a theoretical display with 8 laser primaries thinking that this would improve the metameric result. To his surprise, it was even worse.

The next step was to propose the RIT Multi-Primary Display that is composed of 7 laser primaries. Analysis of this design showed that it might offer the best metameric performance – even better than legacy broad spectrum display. The key, Long found, was in the correct choice of the primaries – not just any primaries.

RIT Multi PrimaryIn the question and answer part, Long noted that the current 2020 primaries are not optimized to reduce metamerism, suggesting a slight change would be helpful in reducing metameric failure.

Analyst Comment

In addition it occurred to us that existing laser projection displays could be improved for 2D content by using all six primaries in the projector. Normally, these are used for 3D, but if all were used for 2D content each primary would be slightly broadened, which should help with reducing metameric failure. (CC)