Digital BW, The Print

There has been some confusion about the relative depth of the blacks in the
MIS VM inkset when used in a 7000 with Mac.  Phil was kind enough to send me
scans of an 1160 Piezo step wedge along with MIS VM step wedges that had
been printed on his 7000-Mac system.

Without altering the files in any way, in Photoshop I measured the luminance
of the 100% black patches of the various test strip scans.  The bottom line
is that the Piezo was a hair blacker.  However, the main visual differences
are due to the distribution of values, not the depth of blacks.  The Piezo
prints much darker.  The details are below.

The 100% black patch for the Piezo had a Photoshop Histogram luminance
reading of 19.22.  (Lower is blacker.) The MIS VM test strips had readings
between 19.95 and 21.35.  This is a maximum 2.13 difference on a 256 scale.
That is, the maximum difference in depth of blacks was less than a 1%.

(I don't know why the MIS VM 100% blacks would differ -- they are all
exactly the same settings.  This may just reflect the normal variance of the
printer.)

The MIS VM curves were unadjusted PC draft curves being printed on a Mac.
So, they were not hitting the marked values right on.  However, they were
not far off, and they were far closer to the marked 21 step wedge values
than was the Piezo test strip.  Here are some representative sample
readings:

Test file 95% patch -- Piezo = 98%, MIS VM = 96%
Test file 90% patch -- Piezo = 95%, MIS VM = 89%
Test file 80% patch -- Piezo = 90%, MIS VM = 81%
...
Test file 50% patch -- Piezo = 68%, MIS vm = 49%
...

So, files that were balanced for this Piezo density distribution would print
very differently with the MIS VM setup.  The 100% blacks would be
essentially the same, but the tones above the 100% black would be
substantially lighter.

However, if one is setting up a new system, I frankly think the linear
response of the MIS VM test curves is a better way to go.

Paul
http://www.PaulRoark.com