[argyllcms] Re: FWA Compensation

  • From: <robert@xxxxxxxxxxxxxxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>
  • Date: Wed, 10 Dec 2014 10:47:52 -0000

OK, great, thanks Graeme.  I was a bit puzzled as the results didn't seem to
add up.

As you are doing a new release, I don't suppose you would be able to add an
option for the i1Pro2 to measure UV on / off for spotread?  i1Profiler has
this feature and it's very useful to get an estimate of how much FWA is in
the paper (for example, with a particular paper the b* reading is -15 with
UV and -4 without ... which gives a good indication of very high FWA
content).  [Also, by looking at the a* reading too it gives an idea of the
extent of the color shift due to the FWA. In the case of this particular
paper b* went from 3 with UV to 0.5 without, so quite a magenta tint caused
by the UV].

As Argyll also allows spotread for a reflective measurement with the paper
(illuminated by the lamp), this would allow three readings: spot white UV on
and off, and reflected white.  If the b* readings were, say, -15, -4 and -6
this would give a comparison between the UV content of the i1 (presumably a
known value?) and the lamp, so that an estimate of the UV content of the
illuminant could be worked out.


-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
On Behalf Of Graeme Gill
Sent: 10 December 2014 01:09
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: FWA Compensation

robert@xxxxxxxxxxxxxxxxxx wrote:

Hi Robert,

> test between the two.  My problem is that I don't really know how to set
> this test, in particular how to know how much UV there is in my
> Perhaps there's an indirect way of estimating that (illumread clearly does
> this, but I don't understand the plots enough to be able to say that
> illumread indicates that this particular illuminant has high UV and this
> has low UV).

Well, the answer is that "illumread -v" will indicate how much
UV it thinks is in the illuminant, in rather arbitrary units.

However, on checking exactly how this works, I'm distressed to discover
that illumread has not actually been working since ArgyllCMS V1.4.0,
when I re-factored some code to add support for M0/M1/M2 :-( :-( :-(.

I've updated <http://www.argyllcms.com/disptools_win32_v1.7beta.zip>
and also updated <http://www.argyllcms.com/Argyll_dev_src.zip>
if you would like to test with a working illumread.

Graeme Gill.

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