World Library  
Flag as Inappropriate
Email this Article

Rec. 601

Article Id: WHEBN0000198207
Reproduction Date:

Title: Rec. 601  
Author: World Heritage Encyclopedia
Language: English
Subject: Rec. 709, Anamorphic widescreen, D-1 (Sony), Color space, Pixel aspect ratio
Collection: Digital Television, Film and Video Technology, Itu-R Recommendations
Publisher: World Heritage Encyclopedia

Rec. 601

International Telecommunication Union – Radiocommunication sector) for encoding interlaced analog video signals in digital video form.[1] It includes methods of encoding 525-line 60 Hz and 625-line 50 Hz signals, both with an active region covering 720 luminance samples and 360 chrominance samples per line. The color encoding system is known as YCbCr 4:2:2.

The Rec. 601 video raster format has been re-used in a number of later standards, including the ISO/IEC MPEG and ITU-T H.26x compressed formats – although compressed formats for consumer applications usually use vertical as well as horizontal chroma subsampling, thus using 4:2:0 sampling rather than directly using the 4:2:2 sampling used in Rec. 601.

The standard has been revised several times in its history. Its edition 7, referred to as BT.601-7, was approved in March 2011 and was formally published in October 2011.


  • Signal format 1
  • Primary chromaticities 2
  • Awards 3
  • See also 4
  • References 5

Signal format

The Rec. 601 signal can be regarded as if it is a digitally encoded analog component video signal, and thus the sampling includes data for the horizontal and vertical sync and blanking intervals. Regardless of the frame rate, the luminance sampling frequency is 13.5 MHz. The samples are uniformly quantized using 8 or 10 bit PCM codes in the YCbCr domain.

For each 8 bit luminance sample, the nominal value to represent black is 16 and the value for white is 235. Eight-bit code values from 1 through 15 provide footroom, and can be used to accommodate transient signal content such as filter undershoots. Similarly, code values 236 through 254 provide headroom and can be used to accommodate transient signal content such as filter overshoots. The values 0 and 255 are used to encode the sync pulses and are forbidden within the visible picture area. The Cb and Cr samples are unsigned and use the value 128 to encode the neutral color difference value, as used when encoding a white, grey or black area.

Rec. 709 chromaticity diagram. The three primary chromacities are almost identical in Rec. 601.

Primary chromaticities

Slightly different primaries are specified for the 625 line and 525 line systems.

RGB color space parameters for Rec. 601
Color space White point (D65) Primary color
xW yW xR yR xG yG xB yB
625 line 0.3127 0.3290 0.640 0.330 0.290 0.600 0.150 0.060
525 line 0.3127 0.3290 0.630 0.340 0.310 0.595 0.155 0.070


The CCIR received a 1982–83 Technology and Engineering Emmy Award for its development of the Rec. 601 standard.[2]

See also


  1. ^ ITU-R Recommendation BT.601: Studio encoding parameters of digital television for standard 4:3 and wide-screen 16:9 aspect ratios, ITU-R
  2. ^ Rec. ITU-R BT.601 25th Anniversary and still "in force" - the bridge that joined the analogue and digital worlds (1982-2007), ITU-R, 2007.
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.