Re: Difference in instruments measurements
Re: Difference in instruments measurements
- Subject: Re: Difference in instruments measurements
- From: Roger Breton <email@hidden>
- Date: Thu, 05 May 2005 08:41:08 -0400
> I went to the IDEAlliance site, but they don't show a picture of what the
> Lab-Ref samples look like.
Actually, I stumbled upon one, on their site. It looks like a tiny series of
1/4" circles placed at 2" from each other on a piece of white material of
about 3" by 7". I think I saw 8 to 10 color samples in all.
> Do they come with a list of the expected L*a*b
> values for each of the patches?
Yes of course.
> If not, how else do they function as
> benchmarks for the integrity of a measuring device?
Right.
> Also, I understand they come already laminated, and the site claims that
> this doesn't affect the readings. Is that true in your own opinion?
I would trust that statement for, as far as I know, they are measured and
certified with the lamination on.
> What is your experience with Lab-Ref? Do you use them, and how do they help
> you? Would you deem them essential for keeping an eye on measuring device
> behavior? Are they worth the $265 investment? And do they drift with time?
They will drift over time for sure. How fast? No idea. As for essential,
it's a function of what your measurement problems are, Marco. I think it can
help answering questions like "which instruments are telling the truth".
But, by design, it's geared toward portable instruments like a 538 or a
SpectroEye. I could conceivably use the Lab-Ref with the DTP41, as Grame
suggested. But I don't see how I could do it with an ICcolor. Also, bear in
mind that there is the issue of UV filtering. I'll bet the readings on the
Lab-Ref represents values *without* any filtering. So, if I have a DTP41
with UV filter or and EyeOnePro with UV filter or a SpectroCam with a UV
filter, well, you see the picture. The whole usefulness of the Lab-Ref, in
my view, hinges upon its stability over time. I know I want a stable
reference that will last me years. Otherwise, it's useless to buy them in
the first place. But it could be a much cheaper alternatives to a set of
Spectralon or BCRA tiles while playing more or less the same role.
It's still a work in progress. But, undoubdtedly, the quality of
measurements we get out of our instruments makes all the difference in the
quality of generated profiles. That is true for all instruments. And it's so
easy to see on comparative printouts. Hence their importance. Some
instruments are easier to track for accuracy and precision than others, like
spectrophotometers. But it should be an important concern, nonetheless. And
since all instruments drift with time, for those who like to think they do
the highest critical color work, periodic re-calibration by the instrument
manufacturer should not even be questioned. I know I do. It costs me but I
get peace of mind. It's an ISO9000 specifications anyway.
> Marco Ugolini
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
_______________________________________________
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