Re: Spectrolino repair
Re: Spectrolino repair
- Subject: Re: Spectrolino repair
- From: Ernst Dinkla <email@hidden>
- Date: Thu, 11 Feb 2016 16:49:25 +0100
I often wonder how papers actually behave to the modelling. For SpectrumViz
I still use an i1 Pro (UV enabled) + i1Share. Its light source is a
tungsten lamp. Depending on the UV range that this lamp covers,
fluorescents in the papers should react. I do not expect that the tungsten
lamp has equal energy in the total UV range it covers and wonder to which
short wavelengths it goes there, The sensor goes down to 380 NM but that
does not describe the lamp output. Could be that i1Share has a model for
the i1 Pro to compensate UV/OBA measuring as well, I do not know.
Whether the OBAs are all one and the same in the papers I measured is
something I doubt, I expect that their UV absorption peaks can differ.
Another factor is TiO2 whitening agent also present in several papers, TiO2
absorbs UV too but does not emit the absorbed energy in the visible
spectral range but beyond that range as heat. It does that in competition
with some OBAs depending on their absorption peaks. The slope in spectral
plots from UV absorption to blue emission/reflectance could be misguiding
with TiO2 present. Having TiO2 in the paper coating and OBAs in the paper
base is not very effective for fluorescence if both act on the same UV
wavelength, however the total UV absorption is measured. BaSO4 whitening
agent does not absorb UV and has no fluorescence for other wavelengths
either so should be quite neutral for any model. Despite the Baryta naming
of several papers the actual BaSO4 content is hard to control and probably
it is used in combination with other normal whitening agents like TiO2.
Certain papers with OBA content and a lack of normal whitening agents can
have a wild spectral plot which may show a flatter spectral reflectance
plot in a UV cut model than they have in reality. For example some Harman
inkjet papers that seem to have a paper construction similar to their
analogue B&W papers that I also measured.
This is what I observe without the knowledge whether the spectral plots I
made have been compensated with a model too where the instrument lacks in
straight UV measuring.
Met vriendelijke groet, Ernst
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
January 2016 update, 700+ inkjet media white spectral plots
On Thu, Feb 11, 2016 at 2:46 PM, Ray Cheydleur <email@hidden>
wrote:
> Graeme is precisely correct, the KM FD series, i1 Pro2 and i1iSis 2 are
> using a modeling process (as does Argyle and i1Profilers OBA module), the
> eXact uses instead an approach using filtered Tungsten with additional
> sources in the UV to provide the spectral power distribution at the
> measurement plane. Either approach is completely valid for OBA’s as they
> are well studied and modeled. The issue comes when you look at other
> potential fluorescing agents. Then the model may, or very likely may not,
> perform as expected and thus the eXact is the better choice for these more
> complex situations.
>
> RayC
>
> Ray Cheydleur
> Printing and Imaging Product Portfolio Manager
> email@hidden
>
>
> Roger Breton wrote:
>
> please forgive my technical ignorance but is there anything fundamentally
> wrong or flawed in the following approach :
>
> It's a modeling approach, the same in principle as used by ArgyllCMS FWA
> compensation,
> and the i1pro2 M1/M2. You calibrate for the media's fluorescent response by
> measuring with the instrument light sources, and then use a model to
> predict how it
> will look under a real D50 spectrum.
>
> Graeme Gill.
>
>
>
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