"In a nutshell, 4:4:4 is uncompressed video."

Reduced color sampling is not usually referred to as compression, because you are not making any attempt to maintain the information you throw out.

Adam Wilt explains it well, but here's a summary for the lazy:
4:4:4 means that you keep all color samples you get from the CCD.
4:2:2 means that you throw away half the color information.
4:2:0 and 4:1:1 throw out 75% of the color information.

"Uncompressed video" is used to refer to video that has not been compressed with DCT or any other algorithm that tries to make a smaller file with a modest loss of picture information.

NTSC DV is 4:1:1 and generates 25 Mb/s of data.
Uncompressed 4:2:2 video generates 270 Mb/s of data. This is more hassle to deal with, so few people use it (mostly the large network studios and a few maniacs like me). The good news is that this is the reason why say ABC studio productions look so much better picture quality wise.

4:4:4 means that you keep all color samples you get from the CCD.
To tie these to Vegas, 4:4:4 is a great way to render something out to be transported to another application like AfterEffects, Combustion, or Commotion.
4:2:2 means that you throw away half the color information.
Excellent means of archiving for multiple format output, without ever worrying about losing quality for future formatting. Larger files, but worth the wait if you have multiple files to output, need future access, or have lots of generated media/stills.
4:2:0 and 4:1:1 throw out 75% of the color information.
PAL DV is 4:2:0, NTSC DV is 4:1:1, HDV is 4:2:0. Nice thing about HDV is you're never going through a colorspace shift when you go from HDV to DVD, other than the 601 vs 709 limitations/issues. and those will go away with HD-DVD and Blu-Ray.

"PAL DV is 4:2:0, NTSC DV is 4:1:1, HDV is 4:2:0. Nice thing about HDV is you're never going through a colorspace shift when you go from HDV to DVD..."

And, surprisingly, this is valid even when compared to PAL. HDV using MPEG-2 means that it uses the same 4:2:0 as DVDs, while PAL's 4:2:0 color sampling is actually different.

Hopefully we are all slowly converging towards fewer standards...

:O)

Just as an aside, anyone know anything about the L*A*B color system?
I've read about it, seems this is what is used with film, if I understand what was being said then it has the advantage of precisely defining what a color will be.
Bob.

From the Photoshop online help file:

L*a*b model
--------------------------------------------------------------------------------
The L*a*b color model is based on the model proposed by the Commission Internationale d'Eclairage (CIE) in 1931 as an international standard for color measurement. In 1976, this model was refined and named CIE L*a*b.

L*a*b color is designed to be device independent, creating consistent color regardless of the device (such as a monitor, printer, computer, or scanner) used to create or output the image.

L*a*b color consists of a luminance or lightness component (L) and two chromatic components: the a component (from green to red) and the b component (from blue to yellow).

From Google:

Lab color uses luminance and brightness settings to optimize color for various devices.
writingprogram.hfa.umass.edu/practicum/definitions.html


A device independent colour space used to create consistent color whatever the device used to create or output an image, such as a monitor, printer, computer, or scanner. It consists of a luminance value (L) and two chromatic values – A from green to red and B from blue to yellow.
www.ephotozine.com/glossary/index.cfm


A three dimensional color space where travel along any axis will yield a specific color to top
dx.sheridan.com/glossary/l.html


The Lab Color mode is based on a model of visual color perception using standards created in 1931 by the CIE.
mywebpages.comcast.net/lawrencephotography/glossary.htm

Bob, have you seen references to LAB color for video?

Rob Mack