[Openicc] Default Rendering Intent

[Chris Murphy]

On Nov 26, 2005, at 7:56 AM, Kai-Uwe Behrmann wrote:

> Do we prefere ICC conformance? This includes a break once more  
> rendering
> intents are allowed or they are otherwise structurised than today. Or
> do we like to discuss this matter and keep this part of the  
> settings API

This doesn't really answer your question but I think what should have  
been done is make Relative Colorimetric + BPC (if available) as the  
default rendering intent for v2 conversions and make Perceptual the  
default rendering intent for v4 conversions.

The notion of perceptual as a default rendering intent for years has  
been demonstrated to produce inferior results most of the time (which  
has been a v2 context).

The default rendering intent in profiles themselves is there as a  
last ditch effort. There's nothing in the ICC spec that says you  
can't ignore it and do things differently. It's ignored on a very  
regular basis by apps that have a user selected option (or default),  
as well as one CMM that does its own thing even when the user  
specifies a particular rendering intent.

So I'd suggest that unless otherwise specified by an application, you  
could just say v2 default is RelCol + BPC and v4 default is  
Perceptual and have the CMM make that decision. It's a lot easier for  
the CMM to have a hardwired default (with or without a user setting  
to change the behavior) rather than have to change it in a bunch of  
ICC profiles themselves (and keep on doing it as you collect new  
profiles). I'd rather have a CMM determine the default. Eventually  
the intent will be determined in a more dynamically, specific to the  
image, as well so all the more reason I find the default rendering  
intent set in profiles themselves to be pointless.


Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
-------------------------------------------------------------
Co-author "Real World Color Management, 2nd Edition"
Published by PeachPit Press (ISBN 0-321-26722-2)