Digital BW, The Print

Joost Horsten wrote:
> First of all, a happy 2007 to you all! I hope in this year the world 
> will not be as black and white as our pictures ;-)

A happy 2007 for all.


> So this probably points to the source of my problems with the EEM/Eboni 
> targets. I have noticed before that the eboni prints are quite 
> sensitive (note my remark on the printer rollers in the original post). 
> I have done nothing special with the targets, neither handled them 
> roughly, but also did not protect them in a special way. The have just 
> been laying around for a day or two. But that's maybe not the way to 
> deal with them.
> 
> Going back to the semi-matte camera target, another, slightly related 
> explanation could be that I did not actually clean the target, but put 
> some tiny bit of grease on them with my finger, thereby "polishing" it. 
> In that way, it might be on optical effect, perhaps similar to the 
> difference between matte and glossy papers. Then again, it would be an 
> inherent effect of the matte print.
> 
> Does this make sense to anyone? 

It could be different on the Eye One but my SpectroCam is 
quite sensitive to the distance to the target and the angle. 
The automatic  measuring setup with an old HP plotter had the 
spectrometer slightly higher at first and the results were 
darker readings. A slightly different angle of the head on the 
patch showed similar changes. I had already made another strip 
guide that allows longer strips to be measured manually and 
that works good. The head doesn't touch the strip but is at 
the right height and a thin PET foil protects the rest of the 
target when the spectrometer is running over it.

I'm an advocate for multiple targets and multiple measurements 
+ averaging. The SpectroCam does that already on its way over 
the patches, between 7-15 readings per patch. But I use more 
targets where possible, the targets printed in another 
direction etc.

An interesting fact about the HP Z3100 and Z2100 is that the 
integrated calibration and profiling measures per patch and 
the dark patches get a longer time for the measurement. 
Something that is difficult to achieve with strip reading or 
one should increase the size of the dark patches.

Any change in the surface of matte black should give different 
readings.


Met vriendelijke groeten, Ernst


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