Color Measurement Accuracy - Reflective mode
Color Measurement Accuracy - Reflective mode
- Subject: Color Measurement Accuracy - Reflective mode
- From: Roger Breton <email@hidden>
- Date: Sun, 22 Apr 2001 09:34:16 -0400
Of all the "afforbable" color measuring instruments out on the market today
is the SpectroCam, made by a company in Holand called Spectrostar. I
remember posts on this list here from people saying good thing about this
instrument (andrew, chris comes to mind) and the fact that Praxisoft
supported this instrument.
Has anyone ever tested the accuracy of this instrument, critically, compared
to a SpetroLino or an X-Rite DigitalSwatchbook or an X-Rite 528 or a 938, or
some other quality spectrophotometer, and found it to be within some
"acceptable" DeltaE range?
This is about interintruments agreements. It's nice to talk about the virtue
of ICC and the rest. But what about the very instruments that we depend on?
And the methods by which we derive color measurement from? I was at Seybold
Boston, lately. And remember seeing that the Spectroscan now ships with a
white backing! And I tought, all along, that as per CGATS x, in order to
make spectral measurements, (on opaque material, that is) one was supposed
to use a black backing!?
Is there a need to validate the measurement we get from a given instrument?
Or should we just take its readings at face value? Are there any color
reference material that comes with "certified" measurements?
I was making measurements on a DataColor, a very nice CIE-based standard
laboratory instrument to formulate inks. And I could not make the
measurements agree with those of a Spectrolino or an X-Rite 938? Not matter
how I configured the instrument. Remember that the DataColor is used
worlwide in formulating printing inks.
So, what is "believable" color? I heard once of an ASTM document number that
outlines a method for deriving tristimulus values from spectral data. And I
remember reding that X-Rite and GretagMacbetch do not implement this
conversion the same?
Any thoughts on this on what color measurements should be in order to be
believable? And yield "trustable" ICC profiles?
Roger Breton
Quibec Institute of Graphic Communications