Re: Convert UV-excluded to UV-included
Re: Convert UV-excluded to UV-included
- Subject: Re: Convert UV-excluded to UV-included
- From: "Chris McFarling" <email@hidden>
- Date: Tue, 22 Dec 2009 12:08:51 -0500
- Importance: Normal
Well, this question then comes to mind: if the measurements are
UV-excluded
(i.e., measured with a UV-excluded spectrophotometer), and the paper data
are measured separately as UV-included (obviously with a UV-included
spectrophotometer), why not make ONE set of measurements instead, just
with
a UV-included device?
It seems like a lot of extra work to do it otherwise.
What got me wondering about this is that a published specification may be
based on UV-included measurements (like GRACoL for example). If someone is
trying to match GRACoL characterization data and the only device they have
to work with is a spectro with a UV filter then there may be no way to
reliably compare measurements. It would come down to the amount of OBA in
the paper. With zero OBA the measurements should be comparable. As the OBA
level in the paper increased, the measurements taken with the UV-cut device
deviate further and further from measurements take with a non-filtered
device.
If there were a standardized UV rating for paper then theoretically it
wouldn't matter what type of device you took the measurements with. Software
could calculate a UVi measurement from a filtered device or it could
calculate a UVe measurement from a non-filtered device. I could see this
being included as part of the paper spec. Just like gloss, brightness,
weight, you could have UV rating.
If there was a way, IMO, to establish a-priori the amount of optical
brighteners in a given substrate, in absolute terms, on some kind of
industry standard scale, then, perhaps, this could be matched with a
graded
system of optical correction. Perhaps. Because, you see, another important
consideration in this UV correction scheme is the "UV content" from the
light sources under *which* the substrate will be viewed: a fixed
correction
maybe adequate for one kind of light source while not enough for another,
or
too much.
That is true but isn't that also a shortcoming of the current method of just
using a non-filtered measuring device? If I take some measurements with a
non-filtered EyeOne the UV included in those measurements is specific to the
light source of that device. The UV content in that light source might not
match another device or the bulbs in my light booth.
From what I understand the XRite iSis may already be doing something similar
to what I was envisioning. Apparently it takes two readings, a filtered
reading which excludes UV and a reading utilizing only UV light. It can
combine the two measurements if you need UVi output. Am I correct in
describing how the iSis works?
_______________________________________________
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