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: Sat, 26 Aug 2006 11:03:22 -0400
Richard,
You should not compare data taken from two different
instruments,
The sentence before this one in my response was:
"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,..."
I should have added the word "geometry" after "two
different instruments" to make it clearer; my mistake. You
can easily compare data from two instruments of the same
geometry, as your customer asks, but not the Eye-One vs a
sphere instrument.
I believe the machine offers 20nm spectral resolution.
And "reported" resolution versus actually measured
resolution may be different. This is just another aspect
that complicates inter-instruments comparison.
They both have SPIN.
I saw that some recent Datacolor model 600 spectros have
both SPIN/SPEX options.
At this point, confirming fluorescence with a simple
spectrum check with an Eye-One with NO UV-cut seems the
way to go.
Regards,
Danny
email@hidden
www.BabelColor.com
Could the fluorescence also uncover the use of
brighteners?
I wouldn't think they would do that but could
brighteners cause such a difference?
Yes, this is how fluorescence affects the color.
The Optical Brightening Agent (OBA), either in the
substrate or the dye/pigment, will do that.
On Sat, 26 Aug 2006 08:14:19 -0500
Richard Brackin <email@hidden> wrote:
On Aug 25, 2006, at 5:26 PM, <email@hidden>
wrote:
Richard,
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.
That is effectively what the customer is having us do.
ColorGuide Sphere 6830 readings vs. DataColor 600
readings.
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.
Yes. I definitely took note of that.
I believe the machine offers 20nm spectral resolution.
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 ;-) )
We'll take a look at your software.
Could the fluorescence also uncover the use of
brighteners?
I wouldn't think they would do that but could
brighteners cause such a difference?
Is your Eye-One a UV-cut model?
The one I'm using is not UV-cut.
We have an eye-one that is a UV-cut model at our other
facility to calibrate/profile our UV presses over there.
Does one or both of your sphere instruments have a
specular-included
(SPIN)/specular-excluded(SPEX) option?
They both have SPIN. I'll have to dig around the menus
and see if they have SPEX but I think they're SPIN.
It's a BYK-Gardner ColorGuide Sphere SPIN model CG-6830
(I should have initially mentioned they were SPIN).
The two devices we have are pretty much identical.
.
Danny
email@hidden
www.BabelColor.com
Thanks for your time and information.
Richard
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden