From: Larry Roohr (lrryr@attbi.com)
Date: 03/09/02-08:59:33 PM Z
Thought I'd report on what I found today on making inkjet negatives with
pictorico and peizography inks. I made step ramps and printed them, so
exactly how these things would show up in practice I cant yet say. There are
two less than ideal aspects.
1. Pattern visible due to Pictorico's zero dot gain.
The Peizo driver uses a non-random pattern that looks like a screen door. I
think Dan's right and it would not show up on papers with texture but it is
quite pronounced in the negative. Also any paper feed or clog issues in your
printer stick out like a sore thumb.
The Epson driver, in 'error diffusion' mode is random enough that the
pattern shows up like a grainy texture, preferable to the peizo driver to
me. In 'fine dither' mode it starts to have form, looks like fine lines
across the negative. Again with textured papers and a well running printer
these shouldn't be a problem.
2. Major curve adjustments to get a linear response from Pictorico.
For instance the adjustment curve I did today for a 1.3 density negative
with the epson driver a 0% to 20% density ramp on screen had to transform
to 0% to 78% to look right on the pictorico. But that end isn't the problem.
A 70% to 100% on screen ramp is transformed to 94% to 96% for what should be
a linear ramp on pictorico. 94% to 96% is what gets sent to the printer to
print 70% to 100%, this results in posterization in 8 bit mode, which is
what the Epson driver runs in, should really screw up the highlights. The
Peizo driver runs in 16 bit mode and this was much improved on the negatives
but still visible.
The 1.3 density negative was just about right for a straight AFO and LiPd
ziatype, if I remember right this expects negatives in the 1.8 to 2 density
range so the ink is more opaque to uv than my densitometer readings.
So I plan to print some zia's with the more contrasty mixes and lower
density neg's tomorrow and see what some images look like.
Larry
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