[argyllcms] Re: More direct method of measuring FWA?

  • From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 23 Jul 2010 05:44:35 -0700

On 2010 Jul 22, at 9:39 PM, Graeme Gill wrote:

> The main weakness in using the FWA compensation is characterising the 
> illuminant.

I've come to realize this on a more visceral level lately. Not long ago I had 
side-by-side samples of some papers, one with and one without brighteners. And 
I just happened to take them from sunlight to fluorescent to incandescent 
lighting in a span of minutes. The difference was dramatic in sunlight, obvious 
in fluorescent, and subtle under incandescent.

If I may suggest? Everybody interested in this topic should find a Tyvek 
envelope and compare it with some cheap bright-white office paper under direct 
outdoor sunlight and then a 60-watt incandescent bulb. Tyvek is almost as good 
as PTFE as a 99%+ flat-spectrum reflector. Most CD envelopes are made of Tyvek, 
and you can get a pack of Tyvek mailers at any office supply store.

> No
> affordable instrument is capable of measuring the Ultra Violet wavelengths.
> In V1.2.0 I have created a new tool (illumread) that provides an indirect way 
> of
> doing this, by making use of the FWA algorithm.

Wonderful! I'm looking forward to it, even (especially) though I now realize 
that it's a far more complex problem than I ever imagined before.



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