[Tig] "video" vs RGB

Bob Friesenhahn bfriesen
Tue Jul 26 23:07:03 BST 2005

For GraphicsMagick I have currently implemented DPX YCbCr support 
which clips below-black and above-white when the file is read.  This 
allows safely scaling to and from full-range R'G'B'.  By mapping 
full-range RGB to the YCbCr video range, a RGB image that looks right 
on a computer display should also look correct as video.

A drawback to this approach is that below-black and above-white 
information in the YCbCr is simply discarded when the image is read. 
Without the discard, it may be that the levels could have been 
corrected.  A video Pluge with below-black will lose its below-black 

So, my question to the TIG experts is how video YCbCr should be 
handled in applications which are principly RGB-oriented?  How do 
major studio applications deal with this issue?

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

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