[Tig] rec 601 rec 709

Dave Corbitt DCorbitt77 at comcast.net
Sat Jun 2 03:33:25 BST 2007


On Jun 1, 2007, at 8:49 PM, Rob Lingelbach wrote:

> Can someone point me to a reference on the web that describes exactly
> the wording of Rec 601 and Rec 709?
>
> thanks in advance.
> Rob

Rob,

Rec 601 is a spec on how component digital SD video is encoded for both 
525 and 625 component digital video systems. This is a transmission 
standard and describes the data rates, how luminance and chrominance 
information is interleaved, the matrix proportions of RGB to create 
Luma, the aspect ratio of the pixels, etc. Here's a quite good tutorial 
and historical view of Rec 601 in pdf format:

www.ebu.ch/en/technical/trev/trev_304-rec601_wood.pdf

If you want the full document from the ITU, you can buy it online. It 
is titled BT.601-6 (01.07)

Rec 709 is actually shorthand for ITU-R BT.709 and describes a 
recommended colorspace for HD and SD video. It also describes the 
matrix proportions for RGB to create Luma and these are different than 
for Rec 601 due to the different colorspace (different color primaries 
call for different proportions for luma accuracy). It is essentially 
very similar to EBU colorspace with some slight modification. Rec 709 
defines the primaries in terms of CIE coordinates. It also describes 
the gamma characteristics of the source and by extension, the display 
device (each is the inverse of the other to create a theoretically 
linear system). See here for a good introduction tutorial :

http://en.wikipedia.org/wiki/Luminance_(video)

Full documentation for Rec 709 can be purchased online from the ITU, 
titled  ITU-R BT.709.

Google searches will give you lots more if you care to weed through it 
all.

Dave Corbitt
FrontNICHE North America
Summit, NJ 07901
http://www.frontnichena.com/



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