Re: Creating ICCs with pigmented inks
Re: Creating ICCs with pigmented inks
- Subject: Re: Creating ICCs with pigmented inks
- From: Graeme Gill <email@hidden>
- Date: Thu, 04 Jul 2002 11:46:36 +1000
Chris Murphy wrote:
>
specific amounts of each wavelength in an illuminant. The light you see
>
is the product of both the spectral reflectance of the ink, the paper and
>
the spectral power distribution of the light source.
Then we agree that the spectral reflectance of the ink doesn't depend
in any way on the illuminant - the point I was making.
>
> One ink
>
>isn't more dependent on the illuminant, they are all completely
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>independent of the illuminant.
>
>
Definitely not.
So you're saying that the ink is photosensitive ???
>
If you have yellow ink on paper, and move to a location
>
where the light source has no emission in wavelengths between 590 and
>
630nm, that yellow ink isn't going to look very yellow. That's an extreme
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example, but the color you get from ink is illuminant dependent.
The perceived color will certainly be dependent on the illuminant (of course!),
but the reflectance characteristics of the ink are not dependent on
the illuminant. Saying that one ink is "more dependent on the illuminant"
than another is nonsense. Saying that the perceived color of the ink
is "more dependent on the illuminant" is an ill-defined statement,
that has unstated assumptions and goals.
Saying that "under illuminants 1, 2 & 3, ink A remains closer in
perceived color to the target than ink B" (i.e. ink A is a better
spectral match to the target than ink B) is a reasonable, well defined
statement.
>
What we
>
see depends not only on the spectral reflectance of the ink + paper, but
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the spectral power distribution of the light source to begin with.
Of course. So why say that the ink depends on the illuminant ?
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No, it's the reason why the color you get from these inks is so dependent
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on what light source they are being viewed under at a given moment in
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time. It doesn't matter what kind of color management you do - curve
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based or table based.
Of course it matters. It matters in achieving a metameric match,
and it matters in trying to achieve at least a first order
spectral match by the choice of black component.
>
Yes, fine, but I want to SEE the results of this effort with my own
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eyeballs. Send me some samples!
I'll see what I can do, but I'm not a salesperson in the US, I'm
a developer in Australia.
>
Hey if you have paper substrates that can do that, I'd like to know where
>
to get some!
All "normal" glossy surfaces do this. Glass, plastic, glossy paper etc.
Take a look through a 3D graphics book that covers basic illumination
models.
Graeme Gill.
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