Re: Colorsync-users Digest, Vol 8, Issue 97
Re: Colorsync-users Digest, Vol 8, Issue 97
- Subject: Re: Colorsync-users Digest, Vol 8, Issue 97
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- Date: Sun, 24 Apr 2011 20:04:32 +0000
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Subject: Colorsync-users Digest, Vol 8, Issue 97
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Today's Topics:
1. Re: UV cut or not for i1 Photo Pro (Ernst Dinkla)
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Message: 1
Date: Sat, 23 Apr 2011 21:19:57 +0200
From: Ernst Dinkla <email@hidden>
Subject: Re: UV cut or not for i1 Photo Pro
To: Robin Myers <email@hidden>, ColorSync Users Mailing List
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On 04/23/2011 07:39 PM, Robin Myers wrote:
> By "UV enabled" I believe Mr. Dinkla was referring to an instrument
> without a UV cut filter, so it is enabling measurement of UV
> wavelengths. In which case he correct in his assertion that it
> measures a wider spectral range.
>
> The UV Cut filter employed in the i1Pro removes all illumination
> below 400 nm. Without illumination there should be no reported data
> in this region. So the actual range for the i1Pro UV (this is
> X-Rite's nomenclature for an i1Pro with a UV-cut filter installed) is
> 400-730 nm in reflectance measurement mode.
>
> However, X-Rite, for some unknown reason, creates and reports
> extrapolated data in the 380-400 nm region. At best this leads to
> false interpolations of data in this region, at worst it creates
> highly erroneous data which causes problems further along. I have
> measured papers with FWA additives that sometimes cause their
> interpolation algorithm to produce values in excess of 200%
> reflectance in the 380-400 nm region.
>
> I have a more thorough report on this issue in my Chromaxion
> newsletter available at
> http://rmimaging.com/information/Chromaxion_Issue_1.pdf.
>
> To remove issues with bad extrapolation data in my SpectraShop
> program, I set the data to 0% reflectance in this range for the i1Pro
> UV and the Spectrolino when used with the UV Cut filter.
>
> Robin Myers
Mr. Meyers described it correctly for the Eye 1 Pro. I use the term "UV
enabled" as in several cases the "UV-cut" models do not have any potential
to measure the shorter wavelengths so do not have to cut UV light out
with a filter. Calling the last "UV-cut" isn't correct, they could be
called "Non-UV" I guess. With about 4 categories it becomes difficult to
call one "Normal".
The ColorMunki in reflective mode measures down to 430 Nm
and copies the 430 Nm result in the data down to 380Nm.
I doubt the Spyder3 is any better on the short wavelengths.
The HP Z3100 etc is measuring with 20Nm intervals at the range of
400-700 Nm. Interpolating down to 10 or 5 Nm when selected in Color
Center measurements export.
I wonder what the "UV cut" mode of the iSis does on wavelength range in
reflective mode. The limitation is in the light source and most likely
that light source is similar to the Z3100 white LED. The optical
interval is 10 Nm.
The SpectroCam (UV enabled) used to measure from 380 to 750 Nm in 5 Nm
intervals.
The best UV enabled spectrometers measure a wider range in general. The
"UV cut" models cut at 400 Nm, the "Non-UV" at 400-430 Nm and their
limit varies between 700-730 Nm at the other end.
--
Met vriendelijke groeten, Ernst
Dinkla Gallery Canvas Wrap Actions
| Dinkla Grafische Techniek |
| www.pigment-print.com |
| ( unvollendet ) |
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End of Colorsync-users Digest, Vol 8, Issue 97
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