Re: Epson Stylus Pro 9600 Extrachrome
Re: Epson Stylus Pro 9600 Extrachrome
- Subject: Re: Epson Stylus Pro 9600 Extrachrome
- From: Roger Breton <email@hidden>
- Date: Wed, 17 Nov 2004 22:03:39 -0500
> The technical term for the phenomenon where a single sample appears to
> change color with a change in illuminant is "color inconstancy".
I got it. It's on page 128 in Burns book. It says : "Colors used in imaging
systems such as photography and printing should lead to minimum inconstancy,
..., because we view photographs and printed documents under a wide variety
of illuminations".
OK. So far so good.
Then, at the top of p. 129, Burns writes: "The eucledian distance between a
sample's colorimetric coordinates under a test illuminant compared with its
coordinates under a reference illuminant indicates the degree of color
inconstancy". Then, there's the equation to calculate the color-inconstancy
index or CII which much resembles a Delta E euqation of some sort because,
just like the Delta E color-difference metric, it is based on a 3D Eucledian
distance concept. So the procedure involves calculating the CIE Lab value of
a sample under two illuminants, finding the differences between their L*, c*
and H* components across these two illuminants, weighted by some Lightness,
chroma and hue term, and take a quare root of that.
At any rate, if I was to measure, say, a 100Y on a Matchprint, a 100Y on a
ColorArt, a 100Y on a press sheet, a 100Y on a dye inkjet and a 100Y on an
UC Epson, would I find a larger color-inconstancy index on the Epson yellow
than on any other pigments? That's an interesting hypothesis to test.
What do you think should be the reference illuminant under his test method:
D50? Makes sense? And then, we calculate the index for tungsten to D50 and
D65 to D50.
> SpectraShop can calculate several different CII values for a sample.
OK. When is SpectrShop going to support the EyeOne? Or other instruments?
Other than the Spectrolino?
> Robin Myers
Regards,
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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