QTR-Quadtone RIP

On 02/13/2013 05:25 AM, Peter Miles wrote:
> Extra equipment needed - a light box
>
> In transmission mode the software asks you to calibrate the eye-one in
> two steps.
> first on the calibration tile, then it asks you to place your spectro on
> your light box
> and click the "Cal Trans" button.
> This sets the light box light as being "spectrally neutral'
>
> Because the calculations are made from the spectral data it would make
> sense to use a light box whose light output does not have spectral gaps
> in it's output.
> Such as the from daylight tri-phoshpor fluorescents or something with a
> reasonably good color-rendering index (CRI).
> I've only tried it with the transparency back light from our GTI viewing
> booth and it works just fine.
> Once we get out day-view light boxed fixed, a horizontal surface light
> box would make it more convent than the vertical surface of the GTI.
>
> You could measure your existing light box with your eye-one on emissive
> mode and just have a look at the spectra.
>
> If you email Robin Myers you can get a fully functional 30 day trail
> copy of the software. Or you could at the time I purchased it (Sep 2012).
>
> regards
> Peter

Ben will not need the transmission density measurement function for his 
workflow. Any reflective spectrometer ot colorimeter that measures L 
values correctly between 5 and 100 and export that in text or CSV is 
what he needs. The rest can be done with QTR tools.

If that transmission density measurement is needed for alternative photo 
processes that use a film positive or negative for a copying step then a 
measurement of the blocking of UV light (the actinic part of the UV 
range) is more appropriate. Which means the meter is question should at 
least measure into UV and the light source used should mainly have UV 
light in its spectrum. It will still not totally represent the copying 
conditions but come closer to that. It is however easier but more time 
consuming to measure an alternative process print target at the end of 
the process in reflective mode and base the curves for the positive film 
on that measurement.

For a display light box positive it makes sense to use the same lamps 
for both the display light box and the measurements. Fluorescents or 
LEDs, even with the best CRI, do not have a continuous spectrum in their 
output but at least there is no difference between the two light 
sources. Not many that need a transmission measurement like that.

-- 
Met vriendelijke groet, Ernst Dinkla

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012: 500+ inkjet media paper white spectral plots.