XvYCC

xvYCC or extended gamut YCbCr 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. xvYCC was proposed by Sony, specified by the IEC in October 2005 and published in January 2006 as IEC 61966 2 4. xvYCC extends the ITU R BT.709 tone curve by defining over ranged values. 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. Deeper hues can be created – for example a deeper cyan by giving the opposing primary (red) a negative coefficient. The quantization range of the xvYCC601 and xvYCC709 colorimetry is always Limited Range.

Camera and display technology is evolving with more distinct primaries, spaced farther apart per the CIE chromaticity diagram. Displays with more separated primaries permit a larger gamut of displayable colors, however, color data needs to be available to make use of the larger gamut color space. xvYCC is an extended gamut color space that is backwards compatible with the existing BT.709 YCbCr broadcast signal by making use of otherwise unused data portions of the signal. The BT.709 YCbCr signal has unused code space, a limitation imposed for broadcasting purposes. In particular only 16 240 is used for the color Cb/Cr channels out of the 0 255 digital values available for 8 bit data encoding. xvYCC makes use of this portion of the signal to store extended gamut color data by using code values 1 15 and 241 254 in the Cb/Cr channels for gamut extension.

xvYCC expands the chroma values to 1 254 (i. e. a raw value of 0.567–0.567) while keeping the luma (Y) value range at 16 235 (though Superwhite may be supported), the same as Rec. 709. First the OETF (Transfer Characteristics 11 per H.273

The YCC encoding matrix is unchanged, and can follow either Rec. 709 or Rec. 601 (Matrix Coefficients 1 and 5). That is achieved when YCC values are "1, 1, any" and "254, 254, any" in B' component. xvYCC709 covers 37.19% of CIE 1976 u'v', while BT.709 only 33.24%. The last step encodes the values to a binary number (quantization). It is basically unchanged, except that a bit depth n of more than 8 bits can be selected:

The XYZ matrix is as specified in Nvidia docs.

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 (in Colorimetry block of EDID, flags xvYCC709 and xvYCC601), and the source needs to signal the actual gamut in use in AVI InfoFrame and use gamut metadata packets 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 and Blu ray. It is also supported by some cameras, like Sony HDR CX405, that does actually tag the video as xvYCC with BT.709 inside Sony's XAVC.

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. "Mastered in 4K" 1080p Blu ray Disc titles can be played on existing Blu ray Disc players and will support a larger color space using xvYCC. On May 30, 2013, Eye IO announced that their encoding technology was licensed by Sony Pictures Entertainment to deliver 4K Ultra HD video with their "Sony 4K Video Unlimited Service". Eye IO encodes their video assets at 3840 x 2160 and includes support for the xvYCC color space.