xvYCC

xvYCC or Extended-gamut YCC (also x.v.Color) is a color space that can be used in the video electronics of television sets to support a gamut 1.8 times as large as that of the sRGB color space.[1] xvYCC was proposed by Sony,[2] specified by the IEC in October 2005 and published in January 2006 as IEC 61966-2-4.

x.v.Color logo

xvYCC was motivated by the fact that modern display and capture technologies often have underlying RGB primaries with significantly higher saturation than the traditional CRT displays, allowing them to handle a wider color gamut. But these devices have been unable to do this without upsetting basic calibration, as all existing video storage and transmission systems are based on CRT primaries, and are hence limited to the CRT gamut.[3]

xvYCC-encoded video retains the same color primaries and white point as BT.709, and uses either a BT.601 or BT.709 RGB-to-YCC conversion matrix and encoding.[2] This allows it to travel through existing digital YCC data paths, and any colors within the normal gamut will be compatible.[2]

The xvYCC color space permits YCC values that, while within the encoding range of YCC, have chroma values outside the range 16–240, or that correspond to negative RGB values, and hence would not have previously been valid.[2] These are used to encode more saturated colors by using a greater part of the RGB values that can be encoded in the YCbCr signal compared with those used in Broadcast Safe Level.[2] For example, a cyan that lies outside the basic gamut of the primaries can be encoded as "green plus blue minus red".[2]. Since the 16-255 Y range is used and since the values of Cb and Cr are only little restricted, a lot of high saturated colors far above the max. 255 RGB space can be encoded. For ex. if YCbCr is 255, 128, 128 in the case of a full level YCbCr encoding (0-255), then the corresponding sRGB is 255, 255, 255 which is the max. luminance encode-able value in this color space. But if Y=255 and Cr and/or Cb are not 128, this codes for the max. luminance but with an added color: minimum one color must necessarily be above 255 and can not be converted to sRGB. Adapted software and hardware must be used during production to not clip the video data levels that are above the sRGB space. This is sadly almost never the case of software working with a RGB core.

These extra-gamut colors can then be displayed by a device whose underlying technology is not limited by the standard primaries.[2]

In a paper published by Society for Information Display in 2006, the authors mapped the 769 colors in the Munsell Color Cascade to the BT.709 space and to the xvYCC space. 55% of the Munsell colors could be mapped to the sRGB gamut, but 100% of those colors could map to the xvYCC gamut.[4] Deeper hues can be created – for example a deeper red by giving the opposing color (cyan) a negative coefficient.

A mechanism for signaling xvYCC support and transmitting the gamut boundary definition for xvYCC has been defined in the HDMI 1.3 Specification. No new mechanism is required for transmitting the xvYCC data itself, as it is compatible with HDMI's existing YCbCr formats, but the display needs to signal its readiness to accept the extra-gamut xvYCC values, and the source needs to signal the actual gamut in use to help the display to intelligently adapt extreme colors to its own gamut limitations.

This should not be confused with HDMI 1.3's other new color feature, deep color. This is a separate feature that increases the precision of brightness and color information, and is independent of xvYCC.

xvYCC is not supported by DVD-Video but is supported by the high-definition recording format AVCHD and PlayStation 3.

On January 7, 2013, Sony announced that it would release "Mastered in 4K" Blu-ray Disc titles which are sourced at 4K and encoded at 1080p.[5] "Mastered in 4K" Blu-ray Disc titles can be played on existing Blu-ray Disc players and will support a larger color space using xvYCC.[5][6]

On May 30, 2013, Eye IO announced that their encoding technology was licensed by Sony Pictures Entertainment to deliver 4K Ultra HD video.[7][8] Eye IO encodes their video assets at 3840 x 2160 and includes support for the xvYCC color space.[7][8]

Hardware support

The following graphics hardware support xvYCC color space when connected to a display device supporting xvYCC:

  • AMD Mobility Radeon HD 4000 series and newer models
  • AMD Radeon HD 5000 series and newer models
  • AMD 785G, 880G and 890GX chipsets with integrated graphics
  • Intel HD Graphics integrated on some CPUs (except Pentium G6950 and Celeron G1101)
  • nVidia GeForce 200 series and newer models
gollark: Which is better.
gollark: Or just one RX580.
gollark: You should demand RX580s instead.
gollark: I've got one with a Pentium 4.
gollark: My mum has a laptop with a Core 2 Duo from about 2009. Somehow it is still going.

References
  1. "HDMI 1.3 Update" (PDF). HDMI Licensing. 2006. Retrieved 2006-08-30.
  2. "xvYCC". Sony Global. Archived from the original on August 29, 2009. Retrieved 2009-08-13.
  3. Naoya Katoh (2007). "New" Extended-gamut Color Space for Video Applications; xvYCC (IEC61966-2-4) (PDF). Hollywood Post Alliance. Retrieved 2009-08-13.
  4. Tatsuhiko Matsumoto; Yoshihide Shimpuku; Takehiro Nakatsue; Shuichi Haga; Hiroaki Eto; Yoshiyuki Akiyama & Naoya Katoh (2006). 19.2: xvYCC: A New Standard for Video Systems using Extended-Gamut YCC Color Space. SID INTERNATIONAL SYMPOSIUM. Society for Information Display. pp. 1130–1133. doi:10.1889/1.2433175.
  5. Richard Lawler (2013-01-07). "Sony to launch 4K digital distribution network this summer, 'mastered in 4K' Blu-ray discs". Engadget. Retrieved 2013-05-30.
  6. Seamus Byrne (2013-05-01). "Sony 'mastered in 4K' Blu-rays a mixed blessing". CNET. Retrieved 2013-05-30.
  7. "eyeIO Delivers Unprecedented Viewing Experience for Sony Pictures Content on Sony 4K UltraHD TVs". Eye IO, LLC. 2013-05-30. Retrieved 2013-06-05.
  8. Todd Sprangler (2013-05-30). "Sony Gears Up for 4K Ultra HD Internet Movie Service". Variety. Retrieved 2013-06-05.
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