A reduced color resolution in digital component video signals. To accommodate storage and bandwidth limitations, the two color components (Cb, Cr) in digital video signals are compressed by sampling them at a lower rate than the brightness (Y). Color information is actually discarded.
YCbCr is the YUV color space recorded digitally. Y is brightness (luma), and Cb and Cr are the U and V color difference signals (see YUV for details). In chroma subsampling, only the colors are compressed, not the luma because the eye is more sensitive to brightness than to the color components.
The 4:4:4, 4:2:2, 4:2:0...
YCbCr is designated as 4:n:n. The 4 represents a sampling rate of 13.5 MHz, which is the standard frequency (ITU-R BT.601) for digitizing analog NTSC, PAL and SECAM. The next two digits represent the Cb and Cr rate. Review the illustrations below for details. Each 8x8 matrix represents a "macroblock" of 64 pixels in a video frame. The pink squares are the pixel locations where the sample is taken. Sony's HDCAM uses a different notation because it compresses both the luma and the colors (see 3:1:1).
4:4:4 (Cb/Cr Same as Luma)
Cb and Cr are sampled at the same full rate as the luma. MPEG-2 supports 4:4:4 coding, but having the same number of color difference samples as the luma is considered overkill and not worth the additional bandwidth to transmit it. When video is converted from one color space to another, it is often resampled to 4:4:4 first.
4:2:2 (1/2 the Luma Samples)
Cb and Cr are sampled at half the horizontal resolution of Y. Co-sited means that Cb/Cr samples are taken at the same time as Y. 4:2:2 color sampling is widely used and considered very high quality. It is used for prosumer and professional digital video recording, including DV (at 50 Mbps), Digital Betacam and DVCPRO 50 and is an option in MPEG-2.
4:1:1 (1/4 the Luma Samples)
Cb and Cr are sampled at one quarter the horizontal resolution. Co-sited means that Cb/Cr samples are taken at the same time as the Y. Co-sited 4:1:1 is used in DV, DVCAM and DVCPRO formats.
4:2:0 (1/4 the Luma Samples)
The zero in 4:2:0 means that Cb and Cr are sampled at half the vertical resolution of Y. MPEG-1 and MPEG-2 use 4:2:0, but the samples are taken at different intervals. By the time MPEG-2 came along, it was known that 4:2:2 coding was often converted to 4:2:0, which is why MPEG-2 sampling more closely lines up with the 4:2:2 pattern. H.261/263 also uses 4:2:0.
Analog Too
Engineers use the 4:n:n nomenclature loosely to refer to relative bandwidths of analog signals. For example, if digital RGB signals (computer graphics) are converted to analog color difference signals (YPbPr), it starts off at 4:4:4 YPbPr. When appropriately filtered prior to sampling, it might be characterized as 4:2:2 YPbPr, which is not an accurate use of the terminology because it is not digital, but it is used. See YCbCr, ITU-R BT.601 and YUV.
Analog or Digital?
No wonder confusion reigns. These outputs on the back of this DVD player are analog, correctly identified as Y, Pb and Pr, not the digital Y, Cb and Cr.
YCbCr is the YUV color space recorded digitally. Y is brightness (luma), and Cb and Cr are the U and V color difference signals (see YUV for details). In chroma subsampling, only the colors are compressed, not the luma because the eye is more sensitive to brightness than to the color components.
The 4:4:4, 4:2:2, 4:2:0...
YCbCr is designated as 4:n:n. The 4 represents a sampling rate of 13.5 MHz, which is the standard frequency (ITU-R BT.601) for digitizing analog NTSC, PAL and SECAM. The next two digits represent the Cb and Cr rate. Review the illustrations below for details. Each 8x8 matrix represents a "macroblock" of 64 pixels in a video frame. The pink squares are the pixel locations where the sample is taken. Sony's HDCAM uses a different notation because it compresses both the luma and the colors (see 3:1:1).
4:4:4 (Cb/Cr Same as Luma)
Cb and Cr are sampled at the same full rate as the luma. MPEG-2 supports 4:4:4 coding, but having the same number of color difference samples as the luma is considered overkill and not worth the additional bandwidth to transmit it. When video is converted from one color space to another, it is often resampled to 4:4:4 first.
4:2:2 (1/2 the Luma Samples)
Cb and Cr are sampled at half the horizontal resolution of Y. Co-sited means that Cb/Cr samples are taken at the same time as Y. 4:2:2 color sampling is widely used and considered very high quality. It is used for prosumer and professional digital video recording, including DV (at 50 Mbps), Digital Betacam and DVCPRO 50 and is an option in MPEG-2.
4:1:1 (1/4 the Luma Samples)
Cb and Cr are sampled at one quarter the horizontal resolution. Co-sited means that Cb/Cr samples are taken at the same time as the Y. Co-sited 4:1:1 is used in DV, DVCAM and DVCPRO formats.
4:2:0 (1/4 the Luma Samples)
The zero in 4:2:0 means that Cb and Cr are sampled at half the vertical resolution of Y. MPEG-1 and MPEG-2 use 4:2:0, but the samples are taken at different intervals. By the time MPEG-2 came along, it was known that 4:2:2 coding was often converted to 4:2:0, which is why MPEG-2 sampling more closely lines up with the 4:2:2 pattern. H.261/263 also uses 4:2:0.
Analog Too
Engineers use the 4:n:n nomenclature loosely to refer to relative bandwidths of analog signals. For example, if digital RGB signals (computer graphics) are converted to analog color difference signals (YPbPr), it starts off at 4:4:4 YPbPr. When appropriately filtered prior to sampling, it might be characterized as 4:2:2 YPbPr, which is not an accurate use of the terminology because it is not digital, but it is used. See YCbCr, ITU-R BT.601 and YUV.
Analog or Digital?
No wonder confusion reigns. These outputs on the back of this DVD player are analog, correctly identified as Y, Pb and Pr, not the digital Y, Cb and Cr.
 | Reproduced with permission from Computer Desktop Encyclopedia. Copyright (c) 1981-2008 The Computer Language Company Inc. All rights reserved. |
Additional Resources
- MediaEdit (zip)
- MediaEdit 3 is the easy-to-use movie editing software designed for the consumer. Experience a better way to edit. Built completely from the ground up with the latest video editing technologies. It supports unlimited media layers, comes with standard filters and transitions, and edits more than just DV. It can edit...
- Software downloads 2008-04-09
- Honestech Claymation Studio (exe)
- With the honestech Claymation, you can easily create stop motion video. Capture images using a digital camera, webcam or DV camcorder, create characters, apply small changes, and add background images and music to create your own claymation movies. Project and WMV formats, Onionskin, Rotoscope and Chroma Key, Audio Recording, and...
- Software downloads 2007-11-19
- Recomposit (exe)
- Recomposit is a digital matting masking and inverse calculation and composition tool, it supports two advanced masking digital matting methods: Bluescreen also called chroma key technology and inside/outside edge. Recomposit can help you isolate the foreground subjects from background with all edge information kept, such as hair and semitransparent area....
- Software downloads 2007-10-18
- Pictures from Phase 2 construction of our poor-man's video studio
- Pictures from Phase 2 construction of our poor-man's video studioHey DaveGood Stuff.Good Job DaveIf I lived closer, I'd lend a hand.Looks Good!Gee building a studio brings back the days back in early 1980, my friends and I had to build the studio for my old radio station.Clicked OK too soonI...
- Discussion threads 2007-08-24
- HVC Color Composer Professional Photoshop Plug-in (exe)
- Master Colors HVC Color Composer plug-in for photoshop adds an intuitive color selection tool that will save time and money. Based on a method for identifying colors based on their color hue, intensity value, and its saturation chroma, the HVC Color Composer plug-in makes selecting colors much more intuitive. Whether...
- Software downloads 2007-06-27
- Kodak boosts digital camera sensitivity
- Kodak boosts digital camera sensitivityNew look at an old ideaThe mathematics to do this have been around for years. The Kodak PhotoCD YCC format is analogous with a luminance channel and two color channels. NTSC television does the same thing. About 30 years ago, R. W. G. Hunt proposed a...
- Discussion threads 2007-06-14
- (Images: Alphabet makes words colorful)
- (Images: Alphabet makes words colorful)I can see what's coming next......an image of, for example, Shakespeare, where the individual pixels spell out all of his plays--a cool problem in identifying a chroma-to-character mapping that achieves that effect.Not so hot if you are colorblind...If the statistics I've seen are accurate, 10% of...
- Discussion threads 2007-05-30
- Theories on Apple TV
- Theories on Apple TVNo need to convertIf Quicktime can play it, so can iTunes. All you need is the right codecs for quicktime and you can play DiVX, AVI and WMV in iTunes without conversion.DVDs, being a physical medium, will need to be converted, though.No needSeems to me that with...
- Discussion threads 2007-02-19
- Chroma Clock ScreenSaver (exe)
- When things are getting out of hand and you are melting in a pool of stress, let the mouse rest, sit back and watch Chroma Clock. It's magic. You'll soon feel all the worries of the outside world melt away, to be replaced with divine inspiration.
- Software downloads 2006-11-28
- Samsung DVD-R135
- Set-top DVD recorders have gone from being an exciting innovation to being one step less boring than VCRs, and even the addition of upscaling technology can't save them. But although it may not inspire rampant gear lust, Samsung's DVD-R135, with its ability to record to DVD coupled with the capacity...
- Product reviews 2006-11-10
- Samsung DVD-HD960
- The 1080p resolution, which combines the benefits of lots of pixels and progressive-scan smoothness, is the latest craze in TV technology, and it wasn't long before upconverting DVD players jumped on the bandwagon. The Samsung DVD-HD960 is one of the first players that can upconvert DVDs to 1080p resolution over...
- Product reviews 2006-11-06
- Denon DVD-2930CI
- Denon's high-end upscaling DVD player, the DVD-2930CI ($850 list), is initially a somewhat confusing product. With Toshiba's HD-A1 HD-DVD player going for $500 and upscaling DVD players costing about $150, who wants to spend $850 for a non-high-def DVD player? Well, plenty of videophiles still aren't quite ready to spend...
- Product reviews 2006-09-07
- Sony DVP-NS75H
- Home-theater enthusiasts are always looking for ways to squeeze more performance out of their current systems. One of the more confusing performance enhancers touted by the consumer electronics industry are HDMI-equipped, upconverting DVD players, which claim to deliver quasi-HD picture quality without having to break the bank for HD-DVD or...
- Product reviews 2006-06-16
- Screenshot Helper (dmg)
- Screenshot Helper shows a full screen window with a solid color or a desktop picture. The easiest way to get a clean desktop for screenshots on Mac OS X is to create a brand-new user account and log in as a brand-new user. But if you need to use your...
- Software downloads 2006-05-19
- Samsung DVD-V9650
- While HDMI with upconversion was a feature once reserved for cutting-edge products geared toward enthusiasts, it's now made its way to less expensive models, including DVD/VCR combo units such as the Samsung DVD-V9650 ($130). Upconversion by a DVD player isn't necessary since every HDTV can do it on its own,...
- Product reviews 2006-05-15
- Philips DVP5960/37
- Editors' Note: We've adjusted the rating to bring it the DVP5960/37 line with recent upscaling DVD players.HDMI-equipped DVD players have suddenly become commonplace this year, to the point where they don't cost much more than a generic DVD player you'd pick up at Wal-Mart. The Philips DVP5960/37 is...
- Product reviews 2006-05-08
- Helios HVD2085
- Upconverting DVD players tout their abilities to make your DVDs look even better on your HDTV. But if you bought your HDTV a few years ago and have only component-video inputs, you're probably out of luck. Because of Hollywood's aversion to delivering high-def via analog, DVD players that are allowed...
- Product reviews 2006-04-13
- Sony DVP-NS70H
- HD-DVD and Blu-ray players are still a way from being mainstream, so upconverting DVD players currently provide the closest thing to a high-def DVD experience. Upconverting DVD players don't magically make DVDs high-definition--there's no high-def picture data on the disc--but they scale the available picture to fit HDTV resolutions. And...
- Product reviews 2006-04-10
- t@b ZS4 Video Editing Software (exe)
- t@b ZS4 Video Editing Software is a video compositing/editing system with more than 120 built-in video effects including excellent color and chroma keying. Other features include custom output video width and height, unlimited tracks and sub-composites, custom speed and direction change for video and audio, and the ability to slave...
- Software downloads 2005-12-28
- The day Rio's music died
- The day Rio's music diedRe: The day Rio's music diedMarkets adjust and there are always winners and losers. Rio will be sorely missed.Well, this clears a few things up, I guess...There have been rumors for months if not more than a year about Rio's follow-up to the Karma,...
- Discussion threads 2005-08-26
Neighboring Terms
Premier Vendor Content Whitepapers, webcasts & resources from our Power Center Sponsors
- Intel IT Data Center Efficiency Initiative - Going Green
-
"See how Intel is consolidating down to 8 global data center hubs through the use of consolidation, virtualization and standardization. The initiative is expected to save Intel $1.8B by project completion.
- See how Intel plans to save $1.8 billion >>
- Visit the all new ZDNet Enterprise Mobility Hub sponsored by Verizon Wireless. It has the latest news, commentary, and resources for your mobile strategy development.
- Read the latest from Matthew Miller's The Mobile Gadgeteer Blog
- Five steps to protect mobile devices anywhere, anytime
- Watch a video about Distributed Antenna Systems (DAS)
- Learn how you can fetch your email from anywhere
- All this and more on the ZDNet Enterprise Mobility Hub
