QTR-Quadtone RIP

Hi all,

As a first step to calibrate a new paper we need to find the blackest 
black the printer is capable of.

I think a colorimeter should be more precise than the human eye, so I am 
trying with the colormunki.

However, numbers per se mean nothing, also, measuring twice the same 
sample gives slightly different results, an any engineer would expect.

What is a significant difference ?

for example, pls see this table:

Printer: Epson R1800, UC Inks, Ink#1 (which I hope is the MK)
Paper: Harman MATT FB Mp

Dark Grayish Brown 	1 	45 	20.63798 	1.31831 	2.700665
Dark Grayish Brown 	2 	50 	19.86762 	1.149479 	2.581927
Dark Grayish Brown 	3 	55 	19.45193 	1.079633 	2.199622
Dark Grayish Brown 	4 	60 	19.00063 	1.036125 	2.080517
Black 	5 	65 	18.80058 	0.933541 	1.84603
Black 	6 	70 	18.62351 	0.913706 	1.684894
Black 	7 	75 	18.91697 	0.857361 	1.656826
Black 	8 	80 	18.78215 	0.76134 	1.581838
Black 	9 	85 	18.99918 	0.73042 	1.576031
Black 	10 	90 	19.14227 	0.730163 	1.361232


What we see is that at 75% there is an inversion, which to me means that 
the paper becomes saturated or however no longer linear.
Remember, here we're in Calibration Mode.

So I would think that 70% is the limit for this paper.

However, from 70% to 65% the difference in L is 0.008 (0.2 in density). 
Is this truly visible to the human eye, even after linearization ?

Thank you for your thoughts

Ciao, Marco.


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