[argyllcms] Re: RGB Printer profiling and ColorSavvy CM2C

  • From: "Alastair M. Robinson" <blackfive@xxxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 03 Aug 2005 18:22:34 +0100

Hi,

Graeme Gill wrote:

I'm working on the project partly for my own satisfaction, and

Yep, I'm familiar with that motivation :)

partly on the basis it's easier to convince people with a working
example, than by merely "telling them so". The latter approach
understandably gets their backs up ...

Sadly, yes. I for one will be watching with interest for your results in the n-colour separation area ;)


It doesn't really change the problem, since the idea is that
the source gamut is contracted and expanded to the PCS gamut,
then the PCS gamut is contracted and possibly expanded to
the destination gamut. If the PCS gamut was a very large one,
and the source simply sat within it, then the destination
mapping would contract the whole colorspace (on the basis
of making the PCS gamut fit), reducing the colorfulness
of the result dramatically. The suggested standard PCS gamut
is a fairly large "printer like" one.

Yes, I do see the problem...

Yes it takes some time (about the same time as generating one
of the B2A tables of a profile), but it's not so bad at medium
resolution on a modern GHz processor. The end result is noticeably
smoother and more accurate.

Very interesting. Time to book some time off work methinks :)

> I have a theory that it is feasible, if the result is cached (on disk),
> and the user has some control over how "high quality" they want the result.
>
> In practice, how often does it happen that every part of every job
> is a new, never seen before source color space ?


Very rare I would imagine.

I seem to remember being told, however, that Argyll can create the gamut mapping based not just on the source profile's gamut, but on the proportion of it used by a particular image. That's a particularly intriguing possibility, but one that would perhaps necessitate a 3.6GHz print server!

All the best,
--
Alastair M. Robinson

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