On Mon, 19 Apr 2004, Editor P.O.V. Image Service wrote:
> One of the most metameric traditional pigments is Cobalt Blue. Take a
> photo of a gorgeous oil that utilizes Cobalt Blue, and almost invariably
> it appears purplish. This is because the cobalt blue converts near IR
> light reflected onto it to a more visible magenta tone, so when scanning
> or photographing artwork incorporating cobalt blue pigments, one needs
> to block as much IR light as possible from falling onto the artwork.
> Or.. if the image is captured via a digital process, one should also
> block as much reflected near IR as possible by adding a
> blocking/hot-mirror filter, as digital capture has heightened
> sensitivity to IR than does the human eye. There is a whitepaper on this
> on the BetterLight website, explaining all the work that has gone into
> simply allowing BetterLight digital backs to properly image artwork
> containing cobalt blue pigments.
Your description of the effect of, for instance, cobalt blue in a
photograph suggests another explanation for emergence of metamerism as
issue... Cobalt blue has been a staple of painting for a long time, and so
have photographs of such paintings - if the color didn't photograph
accurately -- ie too little or too much IR in the photographic light --
wasn't such a big deal. Everybody knew it was a photograph, a
reproduction, not the real thing -- & not perfectly replicating the real
thing.
But an inkjet print IS the real thing (for better or worse as the case may
be). And this kind of flaw or weakness in the *object itself* would be a
much bigger deal.
Judy
Received on Tue Apr 20 13:41:57 2004
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