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. Cheers, b&