[argyllcms] Re: Perceptual intent

  • From: <robert@xxxxxxxxxxxxxxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>
  • Date: Wed, 17 Dec 2014 12:40:37 -0000

Graeme Gill wrote:

"When I look at a profile, I typically measure it's gamut
from the absolute colorimetric data since that represents
the underlying device limit, so it's not clear how you are measuring
a "Perceptual Gamut".

I don't know how GamutVision works this out.  The input to GamutVision is
the Source profile, the Destination profile and the intent chosen.  I assume
that GamutVision must map fully saturated Source values to the Destination
and then use the A2B1 table to get the Lab value.  

Is this the equivalent in Argyll-speak?

collink -v -ip -G BetaRGB.icc iPF6400-Canson-Baryta-310-Argyll-2584.icc
argBetaToBaryta.icm
xicclu -v argBetaToBaryta.icm
xicclu -v -ff -ir iPF6400-Canson-Baryta-310-Argyll-2584.icc

(xicclu crashes when I use this command btw, but it works with 
xicclu iPF6400-Canson-Baryta-310-Argyll-2584.icc . same thing??)

So if I feed RGB values of 1 0 0 to xicclu -v argBetaToBaryta.icm I get RGB
1.0 0.005 0.017.  If I feed these values to xicclu
iPF6400-Canson-Baryta-310-Argyll-2584.icc I get Lab values of 50 79 76 .
which is (I guess) the max red that my printer/paper can produce, based on a
perceptual mapping from BetaRGB.  But no doubt I have got things mixed up.


Robert



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