Digital BW, The Print

Hi,

I am attempting to calibrate my printer output using a calibrated
X-Rite 810 densitometer.  I am using MIS FS inks through an Epson 1160
onto PhotoRag 308 paper; I am on a Mac computer.  I realize that this
question has come up in the past, but practical elements of technique
were omitted.  Below you will find the reflective densitometer
(visual) output vs a 21 step stepwedge.  I did measurements using both
the Randall and Piezography workflows.  If you look at the numbers
carefully, you will conclude as to how shockingly non-linear they are.
 I would have expected, for example that the 50 % reading would have
been close to 1.7/2 = .85.  The Measured value of around 0.6 is WAY
off!

Has anyone else had this experience? I would not think that my paper
choice would have that much effect.  Are there subtle differences in
using a reflective densitometer as opposed to a spectrophotometer to
do the measurements? It would seem that for grayscale work that a
densitometer should be fine.  Please advise.

Thanks!

-John Chervinsky



STEPWEDGE  CONE      RANDALL
100.0     	1.71     	1.77
95.00     	1.54     	1.66
90.00           1.40     	1.57
85.00           1.26     	1.45
80.00           1.15     	1.33
75.00           1.05	        1.20
70.00     	0.96     	1.07
65.00           0.86     	0.95
60.00     	0.78	        0.83
55.00     	0.69            0.76
50.00           0.61     	0.66
45.00           0.54     	0.58
40.00           0.48	        0.48
35.00           0.42     	0.39
30.00     	0.36	        0.32
25.00     	0.29            0.27
20.00           0.24     	0.21
15.00           0.19	        0.17
10.00           0.14            0.13
5.00            0.09	        0.09
0.00            0.05	        0.05