XvYCC
Encyclopedia
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
. xvYCC was specified by the IEC
in October 2005 and published in January 2006 as IEC 61966-2-4.
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.
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. This allows it to travel through existing digital YCC data paths, and any colors within the normal gamut will be compatible.
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. These are used to encode more saturated colors. For example, a cyan that lies outside the basic gamut of the primaries can be encoded as "green plus blue minus red".
These extra-gamut colors can then be displayed by a device whose underlying technology is not limited by the standard primaries.
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. 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
or Blu-ray, but is supported by the high-definition recording format AVCHD
and PlayStation 3
.
Gamut
In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain complete subset of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circumstance, such as within a given color space or by a...
YCC
YCbCr
YCbCr or Y′CbCr, sometimes written or , is a family of color spaces used as a part of the color image pipeline in video and digital photography systems. Y′ is the luma component and CB and CR are the blue-difference and red-difference chroma components...
(also x.v.Color) is a color space
Color space
A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components...
that can be used in the video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
electronics of television sets to support a gamut
Gamut
In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain complete subset of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circumstance, such as within a given color space or by a...
1.8 times as large as that of the sRGB color space
SRGB color space
sRGB is a standard RGB color space created cooperatively by HP and Microsoft in 1996 for use on monitors, printers, and the Internet.sRGB uses the ITU-R BT.709 primaries, the same as are used in studio monitors and HDTV, and a transfer function typical of CRTs...
. xvYCC was specified by the IEC
International Electrotechnical Commission
The International Electrotechnical Commission is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology"...
in October 2005 and published in January 2006 as IEC 61966-2-4.
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
Cathode ray tube
The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...
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.
xvYCC-encoded video retains the same color primaries and white point as BT.709
Rec. 709
ITU-R Recommendation BT.709, more commonly known by the abbreviations Rec. 709 or BT.709, standardizes the format of high-definition television, having 16:9 aspect ratio. The first edition of the standard was approved in 1990....
, and uses either a BT.601 or BT.709 RGB-to-YCC conversion matrix and encoding. This allows it to travel through existing digital YCC data paths, and any colors within the normal gamut will be compatible.
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. These are used to encode more saturated colors. For example, a cyan that lies outside the basic gamut of the primaries can be encoded as "green plus blue minus red".
These extra-gamut colors can then be displayed by a device whose underlying technology is not limited by the standard primaries.
In a paper published by Society for Information Display
Society for Information Display
The Society for Information Display is an industry organization for displays, generally electronic displays such as televisions and computer monitors. SID was founded in 1962. Its main activities are publishing technical journals and running Display Week, its main conference, held in May each year...
in 2006, the authors mapped the 769 colors in the Munsell Color Cascade
Munsell color system
In colorimetry, the Munsell color system is a color space that specifies colors based on three color dimensions: hue, value , and chroma . It was created by Professor Albert H...
to the BT.709 space and to the xvYCC space. 55% of the Munsell colors could be mapped to the sRGB gamut
Gamut
In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain complete subset of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circumstance, such as within a given color space or by a...
, but 100% of those colors could map to the xvYCC gamut. 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
HDMI
HDMI is a compact audio/video interface for transmitting uncompressed digital data. It is a digital alternative to consumer analog standards, such as radio frequency coaxial cable, composite video, S-Video, SCART, component video, D-Terminal, or VGA...
1.3 Specification. No new mechanism is required for transmitting the xvYCC data itself, as it is compatible with HDMI's existing YCbCr
YCbCr
YCbCr or Y′CbCr, sometimes written or , is a family of color spaces used as a part of the color image pipeline in video and digital photography systems. Y′ is the luma component and CB and CR are the blue-difference and red-difference chroma components...
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
DVD-Video
DVD-Video is a consumer video format used to store digital video on DVD discs, and is currently the dominant consumer video format in Asia, North America, Europe, and Australia. Discs using the DVD-Video specification require a DVD drive and a MPEG-2 decoder...
or Blu-ray, but is supported by the high-definition recording format AVCHD
AVCHD
AVCHD is a file-based format for the digital recording and playback of high-definition video....
and PlayStation 3
PlayStation 3
The is the third home video game console produced by Sony Computer Entertainment and the successor to the PlayStation 2 as part of the PlayStation series. The PlayStation 3 competes with Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles...
.
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 SeriesGeForce 200 SeriesThe GeForce 200 Series is the 10th generation of Nvidia's GeForce graphics processing units. The series also represents the continuation of the company's unified shader architecture introduced with the GeForce 8 Series and the GeForce 9 Series. Its primary competition came from ATI's Radeon HD 4000...
and newer models