| Wikipedia: 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 specified by the IEC in October 2005 and published in January 2006 as IEC 61966-2-4.
xvYCC uses the full range of values (0 to 255 in an 8-bit space) to represent colors. In BT.601 and BT.709, RGB colors are represented only by 8-bit values from 16 to 235. This limited range was established to allow for undershoot and overshoot which were attributes of analog TV signaling. With digital TV signaling, there is no undershoot or overshoot, and the values from 0-15 and 236-255 can be used to represent colors. In order to maintain backward-compatibility with earlier standards, the red (R), green (G), blue (B) and white standard colors are still calculated at the same indices in the color space. The wider ranges of digital values allow representation of deeper greens, deeper reds, and deeper blues - and the intermediate colors previously beyond the boundary limit in the CCIR 601 color space.
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.[2] Deeper hues can be created - for example a deeper red by giving the opposing color (cyan) a negative coefficient.
A mechanism for carrying the gamut boundary definition for xvYCC has been defined in the HDMI 1.3 Specification. Although HDMI 1.3's other new color feature, Deep Color, is not required to transport xvYCC color information, it is commonly associated with xvYCC because these features are used together in high-end consumer electronic systems to improve the viewing image quality. Above 480p and 576p, Deep Color systems should use Category 2 HDMI cables (indicated by a logo), which are qualified for link clock rates above 75MHz.[3]
References
- ^ "HDMI 1.3 Update". HDMI Licensing. 2006. http://www.hdmi.org/pdf/HDMI_Insert_FINAL_8-30-06.pdf. Retrieved on 2006-08-30.
- ^ Tatsuhiko Matsumoto, Yoshihide Shimpuku, Takehiro Nakatsue, Shuichi Haga, Hiroaki Eto, Yoshiyuki Akiyama, and Naoya Katoh (2006). "19.2: xvYCC: A New Standard for Video Systems using Extended-Gamut YCC Color Space" in SID INTERNATIONAL SYMPOSIUM.: 1130-1133, Society for Information Display. doi:10.1889/1.2433175. Retrieved on 2008-05-20.
- ^ For EDTV modes (480p and 576p), even the 12-bit Deep Color data can be transported across the link using a clock well below the upper bandwidth limit of Category 1 cables.
External links
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