[argyllcms] Re: Fwd: Question about M1 measurements

  • From: Gerhard Fuernkranz <gfuer@xxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 27 Aug 2014 00:55:59 +0200

Am 26.08.2014 19:44, schrieb Roger Breton:
Isn't the "target" illuminant always D50 in an ICC profile?

The virtual illuminant of the PCS is always D50 by definition, but the PCS 
isn't the color space of your print, but a mathematically defined virtual one.

The desired viewing light source for your print can be whatever you want 
(incandescent lamp, fluorescent lamp, etc.), and the point is to build a 
profile for the print under the actual viewing light source. If you want to 
view your print under D50 light, then you are of course free to choose D50 as 
viewing light source.

Print standards are a different story. They define standardized conditions, 
whose assumptions may or may not match reality. I guess there are more people 
around who read a magazine under incandescent or fluorescent light, than people 
reading their magazine in a D50 viewing booth ;-) But admittedly it would not 
be practical either to sell different variants of the same magazine, each one 
intended for a different viewing light source. So one needs a compromise, even 
if it is not perfect, and the standardized compromise is just D50. If you are 
working in the print business, then you may be forced to comply with standards, 
regardless whether they are optimal in a particular scenario, or not. Your 
personal, individual solution is not bound to any standards, though, and you 
can go the pure scientific way.

Btw: The FWA compensation becomes necessary, if the spectrometer's light source 
does not match the desired viewing light source for which the profile is built. 
If the spectrometer uses an incandescent lamp for acquiring the readings, and 
if the desired viewing light source for the print were the same kind of 
incandescent light as well, then the FWA compensation would not make a 



-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx] On 
Behalf Of Graeme Gill
Sent: 26 août 2014 09:22
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: Fwd: Question about M1 measurements

Roger Breton wrote:
So corrections are "illuminant-dependent" then?
Dependent on the target illuminant, yes of course - the whole point is to 
correct the readings for the target illuminant.

Graeme Gill.

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