Could someone please explain "Colorspace"? at DVinfo.net

Go Back   DV Info Net > Cross-Platform Post Production Solutions > High Definition Video Editing Solutions

High Definition Video Editing Solutions
For all HD formats including HDV, HDCAM, DVCPRO HD and others.


Reply
 
Thread Tools Search this Thread
Old January 24th, 2006, 07:33 AM   #1
Trustee
 
Join Date: Sep 2004
Location: Bristol, CT (Home of EPSN)
Posts: 1,182
Could someone please explain "Colorspace"?

I try to not ask these kinds of questions, but I keep seeing reference to 4:2:2 and 4:2:0 and can't seem to figure out what this means.

I switched from DV to HDV and from what I've read, there is a difference. But what?
__________________
Paul Cascio
www.pictureframingschool.com
Paul Cascio is offline   Reply With Quote
Old January 24th, 2006, 08:29 AM   #2
Inner Circle
 
Join Date: Jun 2003
Location: Toronto, Canada
Posts: 4,750
http://www.adamwilt.com/pix-sampling.html
kind of explains it.
Glenn Chan is offline   Reply With Quote
Old January 24th, 2006, 08:48 AM   #3
Major Player
 
Join Date: Feb 2004
Location: Philadelphia, PA, USA
Posts: 548
Color space refers to the values a computer uses to define color.
Physical space, for example, is defined in 3 dimentions, usually referred to as X, Y and Z.

Color space can be defined a variety of ways.
Red, Green, Blue (RGB); Hue, Saturation, Brightness (HSB) for example.
Most color selection dialogs list values in both RGB and HSB since these are the most common color spaces used in computing.

Video, however, typically records and stores data in a format that (roughly) corresponds to one channel for brightness, and two additional channels for color. The abbreviation for NTSC color space is YIQ and and for PAL it's YUV.

The values you see for video resolution (4:1:1, 4:2:0, 4:2:2, 4:4:4) refer to the data compression used in video colorspace.
Luma/brightness is rarely compressed. This is the first "4" and is the basis for defining the color compression.
4:1:1 and 4:2:0 store the same quantity of data, 1 pair of IQ/UV values for every 4 luma values. The data is simply arranged differently as shown in the link above. 4:1:1 is used for NTSC DV, where 4:2:0 us used for PAL DV.
4:2:2 is common in broadcast formats and HDV.
4:4:4 (no color compression) is generally relegated to HD "digital film" cameras like the CineAlta F950, Dalsa, and Thompson Viper.

Hope this helps.
Have fun.
__________________
Nick Jushchyshyn Matchmoving, Compositing, TD
imdb
Nick Jushchyshyn is offline   Reply With Quote
Old January 24th, 2006, 08:50 AM   #4
Capt. Quirk
 
Join Date: Apr 2002
Location: Middle of the woods in Georgia
Posts: 3,596
I'm sorry, but obviously I am drinking defective coffee... could you dumb it down a bit more for me? I guess I totally missed Adam's point, even with the pictures.
__________________
www.SmokeWagonLeather.us
K. Forman is offline   Reply With Quote
Old January 24th, 2006, 09:03 AM   #5
Major Player
 
Join Date: Feb 2004
Location: Philadelphia, PA, USA
Posts: 548
Here's another try. :)
Video stores images in pixels.
Each pixel can have up to 3 values to define it's exact appearence.
1 value for brightness, 2 additional values that define color. (chromanence (sp?))

Since, when all this stuff was being invented, computers and even analog broadcasting tools, couldn't keep up with the data rate needed to handle all three values for every pixel of every frame, some really clever people figured out a cheat.

Our eyes perceive brightness more accurately than color, so, these clever people figured out that if they simply "skipped" recording 50-75% of the color data, pretty much nobody watching the videos would notice.... and they were right.

So, we have broadcasts and recording equipment that are operating 4:2:2 compression. For every 4 pixels, there are 4 brightness/luma values (for our eyes to perceive clarity) and 2 pixels that have color values (which they "share" with the other two pixels, giving us to general idea about the color of all four pixels). HDV is also recorded to this standard.

DV cheats a little more.
There is only one pair of color values saved for every four pixels, but since all four luma values are recorded, it's generally "good enough" for most common video needs. The arrangement of which color values are stored in NTSC vs PAL are shown in the page on Adam's site.

Clear as mud?
__________________
Nick Jushchyshyn Matchmoving, Compositing, TD
imdb
Nick Jushchyshyn is offline   Reply With Quote
Old January 24th, 2006, 09:17 AM   #6
Capt. Quirk
 
Join Date: Apr 2002
Location: Middle of the woods in Georgia
Posts: 3,596
Much better, but... I understand the first value is brightness- 4, and the second value is color- 1,2, or 4, depending on how much info is stored in the pixels... but what is the 3rd value? Is it a redundancy, or for interlaced images?

Also, is there a way to boost mini DV to the higher color values?
__________________
www.SmokeWagonLeather.us
K. Forman is offline   Reply With Quote
Old January 24th, 2006, 09:41 AM   #7
RED Problem Solver
 
Join Date: Sep 2003
Location: Ottawa, Canada
Posts: 1,365
http://www.nattress.com/Chroma_Inves...masampling.htm

Explains pretty much all about chroma sampling.

And yes, there's things that you can do about it! I sell tools for FCP, G Nicer and G Chroma Sharpen that fix DV chroma very well, and soon these tools will also be available, GPU accellerated in FinalTouch too.

Graeme
Graeme Nattress is offline   Reply With Quote
Old January 24th, 2006, 10:17 AM   #8
Capt. Quirk
 
Join Date: Apr 2002
Location: Middle of the woods in Georgia
Posts: 3,596
Nice Graeme, that really did show a difference. Are your filters going to ever be made available to us non-FCP folks? I'm still using Premiere 6.
__________________
www.SmokeWagonLeather.us
K. Forman is offline   Reply With Quote
Old January 24th, 2006, 10:25 AM   #9
RED Code Chef
 
Join Date: Oct 2001
Location: Holland
Posts: 12,514
That seems to be a very nice text you've made on that subject Graeme. I'll
read it shortly. Thanks!
__________________

Rob Lohman, visuar@iname.com
DV Info Wrangler & RED Code Chef

Join the DV Challenge | Lady X

Search DVinfo.net for quick answers | Buy from the best: DVinfo.net sponsors
Rob Lohman is offline   Reply With Quote
Old January 24th, 2006, 10:37 AM   #10
Major Player
 
Join Date: Feb 2004
Location: Philadelphia, PA, USA
Posts: 548
Quote:
Originally Posted by Graeme Nattress
http://www.nattress.com/Chroma_Inves...masampling.htm

Explains pretty much all about chroma sampling.

And yes, there's things that you can do about it! I sell tools for FCP, G Nicer and G Chroma Sharpen that fix DV chroma very well, and soon these tools will also be available, GPU accellerated in FinalTouch too.

Graeme
ABSOLUTELY FANTASTIC SITE, SIR !!!
I'll be reading for days to catch up. :)
Thanks for sharing.
__________________
Nick Jushchyshyn Matchmoving, Compositing, TD
imdb
Nick Jushchyshyn is offline   Reply With Quote
Old January 24th, 2006, 01:45 PM   #11
RED Problem Solver
 
Join Date: Sep 2003
Location: Ottawa, Canada
Posts: 1,365
Thanks all!

No plans for PC versions of anything. I have my work cut out keeping up with FCP stuff, and the new FinalTouch plugins.

Graeme
Graeme Nattress is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Cross-Platform Post Production Solutions > High Definition Video Editing Solutions

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 03:28 PM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network