[Tig] When to use 444RGB or 444YUV for Dual link monitoring in a DI

[Bob Friesenhahn]

On Sun, 5 Aug 2007, adrian hauser wrote:
>
> So given the above variables when does one select 444YUV
> or 444RGB for dual link monitoring. Aslo when working in
> YUV I have the options to work in full range 0 - 1023 or
> 'video range' 64 - 940.

When transforming from original RGB to YUV, there will always be a 
loss of color since YUV supports a more limited number of colors. 
This is likely an important consideration for when you want to produce 
log output.

For video, Rec.709 defines the transform to and from YCbCr ("YUV") and 
RGB.  It is primarily a YCbCr format which uses "video" levels.  For 
Rec.709 video output you will surely want to monitor results in YCbCr 
space with video range so that you will see the final colors.

As a golden rule, your viewing environment should match the target 
environment as closely as possible in order to assure expected 
results.  Note that if you are sure that your viewing environment 
matches the final translation to the target device environment, there 
may be an advantage to working in the original colorspace (while 
monitoring in the target colorspace) since then you will throw as 
little away as possible and it will be easier to retarget your work to 
some other space.

The term "Full Range" RGB is not very meaningful except to imply that 
the data is not using "video" levels.

Bob
======================================
Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/