[argyllcms] Re: xicclu -g predictability issue

  • From: Elena [service address] <1007140@xxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 27 Jan 2011 16:52:40 +0100

Hello Gerhard

On 27-Jan-2011, Gerhard Fürnkranz wrote:

> I may be wrong, but I have the feeling that the reverse lookups are 
> significantly faster for in-gamut color than for out of gamut colors. IMO 
> collink's LUT creation phase slows down as well when using e.g. -ir instead 
> of -ip, i.e. when a larger number of the colors need to be clipped.

Wow! You're right, just checked! Creating a devicelink profile with -r51 -ip
took about 7 minutes here, while the same thing with -ir is still at 2%
after 30 minutes!

Graeme, are you sure isn't there some subtle bug you never noticed ? How is
that clipped out of gamut colors cause a so big waste of time and resources ?

If so, then think what happens with colprof: even using -ip there are LOTS
(the majority ?) of points in the Lab/XYZ B2A table corresponding to clipped
colors slowing down things terribly - since the source gamut used for
gamut mapping will NEVER cover the entire Lab/XYZ space! Points that after
all will never be used, possibly... If I'm reasoning correctly, of course...


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