Re: Thoughts on Eye-One vs. Eye-One UV...
Re: Thoughts on Eye-One vs. Eye-One UV...
- Subject: Re: Thoughts on Eye-One vs. Eye-One UV...
- From: Graeme Gill <email@hidden>
- Date: Tue, 17 Dec 2002 20:29:04 +1100
Terry Wyse wrote:
>
It uses essentially an incandescent-type bulb as opposed to
>
other light sources such as xenon that would tend to excite optical
>
brighteners in papers. Wouldn't it make sense that a light source that tends
>
to emit a portion in the UV range and thus have this returned to the sensor
>
as "visible" light through optical brighteners TEND to have more UV issues
>
than a light source that emits very little light in the UV spectrum to begin
>
with? Just an opinion.
The logic seems to go "UV triggers the optical brightness, optical brighteners
cause problems in profiling, therefore UV is bad, and filtering it out makes
profiling problems go away".
Nothing could be further from the truth. Real world illuminants
have UV in them too, otherwise the paper manufacturers wouldn't
bother adding optical brighteners, as they're effect would never be seen!
The reality is that, if your profiling package isn't smart enough
to measure and model the effects of UV brighteners (I know of only two
such packages that seem to do so), then the best you can do
is try and match the light source in your instrument with the
type of light source in your expected viewing environment.
A lot of instruments have an incandescent source, and so are
perfect if you are going to view you print in an incandescent
lit environment.
If you're going to view your prints under fluorescent light,
then a UV filter on your instrument may give better results
(fluorescent lights don't emit much UV, because their phosphor
absorbs it in the process of converting it to visible wavelengths).
If you're going to view your prints in unfiltered sunlight, then you
probably need a Xenon lamp based instrument, or you need
to fit the D65 filter to your incandescent source instrument.
Note that all this has little to do with the white point of
the illuminants, and a lot to do with the spectral content
of the illuminants.
Graeme Gill.
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