DCI-P3

DCI-P3 is an RGB color space first defined in 2005 as part of the Digital Cinema Initiative, to be used for digital theatrical motion picture distribution[1] (DCDM[2]). Display P3 is a variant developed by Apple Inc. for wide-gamut displays.

DCI-P3
  • SMPTE EG 432-1:2010
  • SMPTE RP 431-2:2011
The CIE 1931 chromaticity diagram showing the P3 gamut, and the gamuts of some other common RGB color spaces. The corners of the green triangle are the primary colors of the P3 color space. The white points shown here are Illuminant D65 which is used for Display P3, and CCT 6300 K which is used with DCI-P3.
AbbreviationP3
StatusPublished
Organization
AuthorsDCI
Base standardsRGB
Related standardssRGB, BT.2020, DCDM
DomainColor space, color model
Website

History

Development of the standard

In 2005, Digital Cinema Initiatives, LCC in Hollywood, California released the Digital Cinema System Specification version 1.0,[3] which defined the colorimetry of what would become known as the DCI-P3 color space.

According to section 8.3.4 in the specification, the blue primary color is the same as Rec. 709, sRGB, and Adobe RGB, with a dominant wavelength of 464.2 nm. The red primary is a slightly deeper red than sRGB and Adobe RGB, with a dominant wavelength of 614.9 nm.

The most significant difference is the green primary which is much closer to the spectral locus than either sRGB or Adobe RGB. DCI-P3's green primary has a dominant wavelength of 544.2 nm. Adobe RGB's green primary is more blueish with a dominant wavelength of 534.7 nm. sRGB's green primary is more yellowish at 549.1 nm.

DCI-P3 covers 45.5% of the CIE 1931 chromaticity diagram (see inset image), which describes the color gamut of daylight human vision (Photopic vision) as determined experimentally in the 1920s. In that study, participants visually matched a mixture of red, green, and blue "primary" lights to specific, pure monochromatic colored lights. This defined the spectral locus, which is the outer rim of the diagram, and the maximum extent of human color vision.

A more practical gamut is that of reflected surface colors which is described by Pointer's gamut. In this case, DCI-P3 covers 86.9% of Pointer's gamut.[4] Rec.709/sRGB only covers 69.4%.

While DCI-P3 was developed by the Digital Cinema Initiatives (DCI) organization, many of the relevant technical standards are published by the Society of Motion Picture and Television Engineers (SMPTE) such as SMPTE EG 432-1 and SMPTE RP 431-2.[5]

On November 10, 2010, SMPTE published SMPTE EG 432-1:2010, which includes a variant of the color space using a D65 white point (about 6503.51 K) instead of the ~6300 K white point of DCI-P3.[6]

On April 6, 2011, SMPTE published SMPTE RP 431-2:2011 which defines the reference viewing environment.[7]

DCI-P3 colors are supported in CSS[8] on Safari since 2017 (version 10.1) and Google Chrome since March 2023 (version 111) browsers.[9]

Display technology

Initially, DCI-P3 was available with theatrical xenon-arc projection systems. This emerging technology presented challenges for filmmakers working with digital media on desktop workstations—that is, how to accurately view the colorspace of the theatrical viewing environment during the production and post production process.

In 2008,[10] HP released the first "HP DreamColor" monitor[11][12] which could display 97% of DCI-P3 color space.

In 2014, Eizo introduced the first professional 4K monitor with support of the P3 color space.

In 2015, Apple's iMac desktop became the first consumer computer with a built-in wide-gamut display, supporting the P3 color space. Apple's implementation, known as Display P3, uses a D65 white point, and uses the sRGB tone reproduction curve (sometimes referred to as gamma).

In 2016, the UHD Alliance announced their specifications for Ultra HD Premium which requires devices to display at least 90% of the DCI-P3 color space (in area, not volume).[13][14]

Also in 2016, Apple, Samsung, and Microsoft released mobile and desktop devices with P3 support.

P3 colorimetry
DCI P3 RGB color cube (image encoded with an ICC profile).
RGB color space parameters[4][15]
Color space White point CCT Primary colors
xW yW K xR yR xG yG xB yB
P3-D65 (Display) 0.3127 0.3290 6504 0.680 0.320 0.265 0.690 0.150 0.060
P3-DCI (Theater) 0.314 0.351 6300 0.680 0.320 0.265 0.690 0.150 0.060
P3-D60 (ACES Cinema) 0.32168 0.33767 6000 0.680 0.320 0.265 0.690 0.150 0.060

DCI-P3 specifications are designed for viewing in a fully darkened theater environment. The projection system uses a simple 2.6 gamma curve, the nominal white luminance is 48 cd/m2 with the white point defined as a correlated color temperature of ~6300 K. It is incorrect to refer to this as "D63" as this white point is not a CIE standard illuminant, and is not on the Planckian locus. Instead, the white point is slightly greener. This resulted from optimizing for best light output with the xenon arc lamp projectors commonly used in theaters.[6]

Display P3 is a color space created by Apple Inc.[16][17] It uses the DCI-P3 primaries, but instead of the ~6300 K white point, Display P3 uses the CIE standard illuminant D65 as the white point, which is the most common standard for self-illuminated displays and devices (sRGB and Adobe RGB both use D65). Also, unlike the DCI-P3 projection gamma of 2.6, Display P3 uses the sRGB transfer curve, which is approximately equivalent to a display with a 2.2 gamma.[18] Display P3's gamut is approximately 50% larger than sRGB in volume and 25% in surface.[19]

Since iPhone 7, the built in camera creates images tagged with the Display P3 ICC profile.

P3-D65 with the PQ TRC is also used for some of Netflix deliverables, including HDR and without BT.2020 container,[20][21] but later Netflix added BT.2020 primaries too.[22] Red of P3 is slightly outside BT.2020 triangle.

DCI-P3+ and Cinema Gamut
Color space White point CCT Primary colors
xW yW K xR yR xG yG xB yB
DCI-P3+ 0.314 0.351 6300 0.740 0.270 0.220 0.780 0.090 -0.090
Cinema Gamut 0.3127 0.329 6504 0.740 0.270 0.170 1.140 0.080 -0.100

An expanded gamut known as the DCI-P3+ color space is also available, which in turn is a smaller version of the Cinema Gamut color space.[23] DCI-P3+ uses the same ~6300 K white point as DCI-P3. Cinema Gamut is specified as having a D65 white point.

References
  1. "Color spaces". Technicolor SA. Archived from the original on 2016-02-03. Retrieved 2016-02-01.
  2. "Digital Cinema Initiative Distribution Master (DCDM), Version 1.0". www.loc.gov. 2022-04-11. Retrieved 2022-11-21.
  3. Digital Cinema System Specification V1.0 (PDF). Digital Cinema Initiatives, LLC. 2005.
  4. Kid Jansen (2014-02-19). "The Pointer's Gamut". tftcentral. Retrieved 2018-12-13.
  5. The Society of Motion Picture and Television Engineers, 2011, New York: RP 431-2, D-Cinema Quality – Reference Projector and Environment for the Display of DCDM in Review Rooms and Theaters
  6. "EG 432-1:2010 - Digital Source Processing — Color Processing for D-Cinema". Institute of Electrical and Electronics Engineers. 2010-11-10. doi:10.5594/SMPTE.EG432-1.2010. ISBN 978-1-61482-039-0.
  7. "RP 431-2:2011 - D-Cinema Quality — Reference Projector and Environment". Institute of Electrical and Electronics Engineers. 2011-04-06. doi:10.5594/SMPTE.RP431-2.2011. ISBN 978-1-61482-243-1.
  8. "Wide Gamut Color in CSS with Display-P3". March 2, 2020.
  9. "CSS color() function". Can I use...
  10. "HP DreamColor LP2480zx". Studio Daily. 2008-07-01. Retrieved 2021-07-02.
  11. "Two days with HP and DreamWorks". JusTech'n. 2008-06-10. Retrieved 2021-07-02.
  12. "HP, DreamWorks Preview Breakthrough Color Display Technology | CreativePro Network". 2008-04-16. Retrieved 2021-07-02.
  13. "UHD Alliance Defines Premium Home Entertainment Experience". Business Wire. 2016-01-04. Retrieved 2016-02-01.
  14. Andy Vandervell (2016-01-06). "What is Ultra HD Premium? New HDR standard explained". TrustedReviews. Time Inc. UK. Retrieved 2016-09-19.
  15. Rajan Joshi; Shan Liu; Gary Sullivan; Gerhard Tech; Ye-Kui Wang; Jizheng Xu; Yan Ye (2016-01-31). "HEVC Screen Content Coding Draft Text 5". JCT-VC. Retrieved 2016-01-31.
  16. "The Wide Gamut World of Color — iMac Edition". www.astramael.com. Retrieved 2022-01-22.
  17. "Apple Developer Documentation". developer.apple.com. Retrieved 2022-01-25.
  18. "displayP3 - CGColorSpace". Apple Developer Documentation. Retrieved 2017-08-18.
  19. Dean Jackson (2016-07-01). "Improving Color on the Web". WebKit. Retrieved 2016-09-19.
  20. "Netflix Full Licensed Technical Specification v9.1". Netflix Partner Help Site. Retrieved 2021-03-25.
  21. "Netflix Talks Dolby Vision and HDR10". Streaming Media Magazine. 19 June 2017. Retrieved 11 April 2021.
  22. "Full Non-Branded Delivery Specification v9.2". Netflix | Partner Help Center. Retrieved 2022-09-24.
  23. "PUB DIM-1102-000" (PDF). DCI-P3+ and Cinema Gamut. Retrieved 2021-08-27 – via Document is hosted on Canon's website at canoncanada.custhelp.com/app/answers/answer_view/a_id/1027929/~/extended-color-gamut-information.
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