[argyllcms] Re: Question regarding gamut mapping for photographic images

> Can I achieve this when I create a printer profile with Argyll? Is this, in
> fact, simply what a perceptual intent normally does?
> 
> Regards,
> Greg.
> p.s Currently waiting for my sRGB perceptual tables to compute, for a "high"
> quality profile. It's very, very, VERY slow! ;^)

Hi Greg,

To my knowledge, Perceptual mapping is an art few profiling applications
will reveal the details of. You can read what Jan Morivic has to say about
it in the litterature but you could reverse-engineer existing profiles to
learn if the underlying approach is consistent with what Tom Lianza
discussed in his post. Most profilers use some kind of S-Curve or otherwise
known sigmoidal perceptual lightness mapping to compress the input lightness
range into the output lightness range. Others could use straight linear
techniques. Others, yet, as Tom suggest use gamma curves.

If you want to probe how your profiles are built, I'd suggest you start with
a grayscale in Lab and transform it, perceptually, to your choice of output
profile, measure it and plot the result in Excel to see graphically what is
going on.

BTW, I also found the making of argyll high quality profile on a Mac OSX 733
Mhz G4 to be very slow. One instance I recall was 5 hours! But on a PC, it
just zooms by. Thought you might want to know this.

Regards,

Roger Breton  |  Laval, Canada  |  graxx@xxxxxxxxxxxx
http://pages.infinit.net/graxx

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