Rec. 709

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Rec. 709, as ITU-R Recommendation BT.709 is commonly known, standardizes the format of High-definition television. Rec. 709 and sRGB are sometimes used interchangeably. However, Rec. 709 specifies the capture and transfer characteristics of an HDTV signal, and sRGB specifies a reference monitor that can be used to view that HDTV signal.

1 Technical details
2 References

[edit] Technical details

[edit] Resolution

Rec. 709 specifies two different sets of resolutions: Part 1 codifies older 1125-line and 1250-line HDTV systems, and Part 2 codifies new 1080-line systems. The Part 1 systems are obsolete and should not be used.^[1]

The Part 2 systems are 1920x1080 resolution with square pixels, for a 16:9 (widescreen) aspect ratio.

[edit] Digital representation

Rec. 709, and all systems derived from it (e.g. MPEG-2 and thus ATSC and DVD), use eight-bit code value (CV) 16 for black and CV 235 for white. This is very different from personal computers, which use CV 0 for black and CV 255 for white.

[edit] Colorimetry

**RGB color space parameters**^[2]
Color space	White point		Primaries
Color space	x_W	y_W	x_R	y_R	x_G	y_G	x_B	y_B
ITU-R BT.709	0.3127	0.3290	0.64	0.33	0.30	0.60	0.15	0.06

[edit] Transfer characteristics

Rec. 709 R, G, and B signals E'_R, E'_G and E'_B have a 1/2.2 gamma applied.

[edit] References

The relevant standards are:

ITU-R BT.709-5: Parameter values for the HDTV standards for production and international programme exchange. April, 2002. Note that the -5 is the version; previous versions were -1 through -4.
sRGB: IEC 61966-2-1:1999

See also pgs. 239 (primaries) and 263 (transfer) of Poynton, Charles (2003). Digital Video and HDTV Algorithms and Interfaces. Amsterdam: Morgan Kaufmann. ISBN 1-55860-792-7.