Re: Measurement Geometry
Re: Measurement Geometry
- Subject: Re: Measurement Geometry
- From: Ken Fleisher <email@hidden>
- Date: Fri, 17 Feb 2006 01:09:13 -0500
On Feb 16, 2006, at 6:45 PM, Graeme Gill wrote:
Surely you can have 45/0 geometry, and still illuminate the sample from
all directions ? (Sensor at 0, a ring of lighting at 45).
Yes, of course you are right. In my mind I was thinking of
bidirectional illumination, but even that does not fit my analogy very
well.
According to the information on the Hunterlab web site,
0/45 instruments a designed to measure the appearance of
color. They "see" like we do, and allow for the effects
that gloss, texture and directionality on the color
appearance.
The integrating sphere instruments do the opposite,
they measure the color in a manner that is independent
of the gloss, texture and directionality. They
effectively measure the "underlying" color of
things, so are useful for checking color formulations and
product consistency, particularly for materials with difficult
optical characteristics (gloss, transparency, translucency,
texture).
Graeme Gill.
Again, this is an accurate and good explanation. (I knew I should not
have posted so hastily!) Please ignore the analogy I made as it is not
a very good one for this purpose.
However, I think everything else I stated is pretty accurate--45/0 is
sensitive to measurement of textured samples and d/0 is "in general" a
more accurate way to measure the color of textured samples. 45/0 can be
used in many cases but average multiple measurements (with replacement)
is likely going to improve the accuracy of the results, particularly
when we are talking about measuring targets for ICC profile building.
Ken
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