Quattron

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Diagram of Quattron's 4-pixel structure.

Quattron is the brand name of an LCD color display technology produced by Sharp Electronics. In addition to the standard RGB (Red Green and Blue) color subpixels, the technology utilizes a yellow fourth color subpixel (RGBy) which Sharp claims increases the range of displayable colors,[1][2] and which may mimic more closely the way the brain processes color information.[3][4] The screen is a form of multi-primary color display, other forms of which have been developed in parallel to Sharp's version.[5][6]

The technology is used in Sharp's Aquos LCD TV product line, particularly in models with screens 40 inches across and larger.[7] The technology, distinct from the product line, has been advertised featuring George Takei as the spokesperson in the debut commercial, in which he uses his catchphrase "Oh My".[8] Another commercial had Takei advertising the 3-D model with the Minions from the 2010 movie "Despicable Me".[9]

Criticism[edit]

According to an analysis published in MaximumPC Magazine by Raymond Soneira, president of DisplayMate Technologies, a video calibration equipment producer, Sharp's Quattron technology does not have the ability to show more colors than a standard RGB set. He argues that, due to industry-standard color spaces used by content providers, there is no existing source material that contains the fourth color channel. He further states that any "extra" colors displayed must simply be created in the television itself through video processing, resulting in exaggerated, less accurate color.[10]

Analysis of Quattron[edit]

Color researchers at Queen Mary University of London investigated the Quattron technology and found that although Quattron does have 4 physical color sub-pixels it does not have a fourth primary in the backlight to drive it (yellow is approximately 575 nm). Quattron has a yellow sub-pixel but the manufacturer has not made any provision to produce the yellow light needed to pass through it. On that basis they conclude that it serves no useful function.[11]

The lack of a fourth primary is clearly shown by a spectrogram where the red primary is given separately from the green primary. Yellow may be seen to be simply the sum of red and green. A yellow push may also be observed when yellow is compared with the red and green primaries. The spectral power of yellow is approximately twice that of red and green. Yellow colors will therefore appear more prominently on a Quattron display than red or green colors, but this is because the manufacturer has 'pushed' yellow to a higher luminance rather than having improved the color to more closely approximate a natural yellow (such as the yellow of a sunflower), which has a flat spectral power distribution from lime-green to deep red wavelengths. Green dominates the Quattron yellow and this is confirmed perceptually by color matching.[11] The human visual system is particularly sensitive to yellow, and as a result of the lack of a yellow primary (or a yellow boost to either red or green) there will be difficulty in discriminating between green, red and yellow. The reproduction of a yellow image will as a result always be perceived as slightly green or slightly red (or orange) but never a pure natural yellow.

Spectral response of a common Quattron display. The white response was compared with each of the 4 primaries, given by the respective colored line. All primaries were set to their respective 8-bit RGB maximum, with the exception of equalized yellow where G was reduced by 20%. The model tested is LC-40LE811E, which uses LED backlighting. Spectrometer used was an X-Rite i1Pro, which produces 118 data points between 350 and 740nm.

See also[edit]

  • Color depth
  • Gamut
  • Trichromacy, scientific description of the RGB model for human vision
  • Tetrachromacy, a different biological system than trichromacy, possibly found in some people
  • Opponent process, a color theory which considers yellow a primary color in addition to the classic RGB color model.[3]
  • PenTile (RGB reproduction via RGBG, RGBW etc.)

References[edit]

External links[edit]