Re: Measuring Delta E from two different spectrophotometers
Re: Measuring Delta E from two different spectrophotometers
- Subject: Re: Measuring Delta E from two different spectrophotometers
- From: <email@hidden>
- Date: Fri, 25 Aug 2006 18:26:07 -0400
Richard,
The Eye-One is a 45-degrees/0-degrees instrument, compared
to your two sphere instruments, and assuming
specular-included (SPIN) measurements, the L* values
should be slighly lower for glossy samples in the Eye-One
case. You should not compare data taken from two different
instruments, as you mention in your point 2. Also, Eye-One
Share uses a 2 degrees Observer and your other data was
computed with the 10 degrees Observer; not to be done
also.
Your point 3, about various resolution for different
instruments goes in line with my comment (in my first
response) on the sharp cut-off often seen on (bright)
yellow, orange and red colors.
Oh, and yes.
It's a very, very, VERY bright orange.
Hum!!! Look at the spectrum with the Eye-One. If it goes
over 100 at some wavelengths, around 590 nm, you have your
answer on fluorescence. (Note: You can also use the
BabelColor software in demo mode for this measurement ;-)
)
Is your Eye-One a UV-cut model? (I presume it is not)
Does one or both of your sphere instruments have a
specular-included(SPIN)/specular-excluded(SPEX) option?
This option can be computer or manually controlled
depending on instruments. If yes, make sure the
mesurements were done in the same configuration.
Danny
email@hidden
www.BabelColor.com
On Fri, 25 Aug 2006 15:31:53 -0500
Richard Brackin <email@hidden> wrote:
We just did another test.
We compared the readings from the Gretag Eye-One Photo
vs the ColorGuide Sphere.
Those are the two items we have in house.
The Eye-One measured a 2.4 delta E difference (using
Eye-One Share Software)
The BYK-Gardner measured 11.9 delta E difference on
exactly the same patch.
The Eye-One Share software is calculating delta E using
LAB (CIE 1976, just as the BYK Gardner is currently
configured)
Digging around, I found a cached PDF on the former
BYK-Gardner site.
The following three items caught my attention, and some
have already been brought up here.
1. Traceability to different institutes like NPL or NIST
2. Different instrument design (opticcal principle, size
of sphere, light source)
3. Different spectral resolution (10 or 20nm); has a big
influence when colors with sharp reflection curves are
measured.
Oh, and yes.
It's a very, very, VERY bright orange.
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