Digital BW, The Print

----- Original Message -----
From: "lyonscox" <lyonscox@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Thursday, March 14, 2002 3:31 AM
Subject: Re: [Digital BW] Using MIS VM inks, a question ongoing


> Martin,
>
> I'm going to politely disagree with your conclusion below My monitor
> matches the output just fine for the Lyson inks/3000 and OEM's in C80.
>
> > Even though your monitor may be calibrated it is not matched to the
> printer output with a proper monitor profile. So you are operating in
> the dark a bit << SNIP >>

Cleavis,

I am sorry if I offended, that was not my intent. However, if there is not a
profile or custom dot gain curve or other software or a matching of inks to
standard colro spaces to establish a relationship between the on screen
tones to your print tones, then what you see on the monitor does not
accurately show what will be on the print. Generally the VM inks seem to be
reasonably close to a standard calibrated monitor but there were times with
some images where it seemed like I had to have a very dark screen image in
order to get a properly "exposed" print.

I though you had said that for the Lyson inks you are using just such a
piece of software in the form of an ICC printer profile from Conetech which
would indeed give you a monitor image to match the print. The OEM inks are
matched to the Epson driver and everything is set to match standard color
spaces. What I am saying is that ideally you need the same type of thing for
the MIS VM. A profile for every ink/paper combination you use would of
course be the ideal but fortunately there is enough overlap that it is not
really necessary. Lacking an ICC profile you can manually match a custom dot
gain curve to a printed step wedge which will give you on screen grayscale
tones closer to the print. This is part of the setup procedure for Piezo
software.
>
> > with the curves you need to print a reference step wedge, make a
> change in the curves, print another wedge, compare the difference,
> adjust the curve,print a wedge, etc. until you are getting the smooth
> tonal ramp you want.
> >
>
> This IS what I'm trying.  Just not sure I'm using the best route.

The curves are made on a basis of trial and error and experience to fine
tune the prints. You said that the prints you are getting are lighter than
your image on your screen. To handle this I recommend adjusting what the
monitor shows rather  than by changing the seperation curves. You can have
multiple monitor profiles for different tasks.

When you print a 21-step wedge does it match what is on screen? If there is
a big difference, tackle it from the monitor side. Do a custom dot gain
curve for your working grayscale space. If the tonalities of the wedge are
not smooth then adjust the seperation curves.

Also remember a screen-to-print match in very helpful but is not strictly
necessary. Just like a traditional darkroom you can adjust what you do to an
image based upon the previous print.

>
> ?? To darken the output ??
>    A - lower ALL points in the curves equally ??

You are likely to lose the smooth transitions into black and into white.

>    B - use the "brightness" slider in the printer box ??
>    C - use a single color slider in the printer box ??
>    D - adjust "Gamma" setting from 1.8 to 1.5 in printer box ??

Generally adjusting any of these does more harm than help. The seperation
curves are treating the Epson driver as a black box and once you change
these setting you are changing the insides of that black box which may give
you unpredictable results.
>
> ?? If a curve has is shaped ~ shouldn't they be adjusted so no point
> is lower than the preceeding ??

The extreme shapes are there to trigger the Epson driver to turn different
inks on or off at the tonal points desired. They can get pretty strange
looking when you are trying to turn the tone inks fully on or fully off,
something the Epson driver wasn't really built to do.
>
> It looks like the blue channel in all the 1270 and 1280 curves have
> points lower on the scale towards the right (hence ~) than preceding
> points.  In a regular workflow this would produce
> posterization/solarization.  I'm wondering how it applies for the VM
> ink, since it goes against my simple logic in my simple head ;-)

The thing to keep in mind is that they are seperation curves. They are
trying to force the printer to use certain inks or combinations of inks to
print in specific tonal areas. In color all six inks are spread over a
longer segments of the tonal range. You can do that with the grayscale inks
as well but then as the black and darker grays move up into the lighter
tones the dot pattern becomes more obvious. So once again we are using
something to accomplish a task it was never intended for, but do quite well
all things considered.

Martin