Digital BW, The Print

From:  Dan Culbertson <danculb@c...>
Date:  Thu Sep 14, 2000  12:28 am
Subject:  Re: 1160, Quads and Profiles

 

> I just purchased an Epson 1160 for printing b&w images with 
quadtone inks,
> probably the warm tone Luminos monchromes.  (but I'm open to 
suggestion)
> When using my 750 to print color I use Profiler RGB to profile my 
paper/ink
> combo, but it just dawned on me that this approach may not work on 
the 1160
> since I'll be using monochrome inks.  Am I wrong about this?  If 
so, how
> does one profile paper/ink combos for monochrome ink?  The printer 
hasn't
> arrived yet, so the answer may be self evident when it does, but I 
was
> wondering...
> 
> STEPHEN    JENNINGS

Profiler RGB will create an RGB profile for quad sets but the profile 
will
not separate the channels optimally.  To do that you need to separate 
the
light inks into the light tones and the dark inks into the dark tones 
and an
RGB profile just won't do that.  Here are two "rocket science" ways 
to get
there:

CMYK printing with a RIP (like PressReady)
1.  Duplicate the grayscale channel three times so you have a 
Multichannel
mode file with four identical channels.
2.  Convert to CMYK mode.
3.  Using a CMYK curves adjustment layer separate the light tones 
into the
light ink channels and the dark tones into the dark ink channels 
(this is
*not* an easy task).
4.  Print to the RIP in CMYK mode.
Note - to "profile" the paper ink combination make a CMYK profile in
Profiler RGB.  Use this profile to set the CMYK *preview* only (ie 
don't use
it to separate channels with a mode change).  This will give you a 
pretty
good idea of how the manually separated channels will print.

RGB printing with separated channels (more or less)
1.  Convert a grayscale step gradient to RGB.
2.  In Photoshop create a new "Selective Color" adjustment layer.
3.  Change the Blending Mode to from "Normal" to "Color"
4.  Set the "Method" to "Absolute."
5.  Under "Colors" select the Whites, Neutral, and Blacks - your goal 
is to
colorize the whites to the color of your light ink channel, the 
neutrals to
the colors of the two mid tones, and the blacks to the color of the 
darker
mid tone and black.  For a Light, Midlight, Middark, Black = YMCK ink
sequence you might try White = -24 Magenta + 100 Yellow,  Neutrals = 
+10
Cyan =100 Magenta, -10 Yellow, Blacks = -20 Cyan, -40 Magenta, -50 
Yellow.
For this inkset gradient should become a rainbow from yellow to 
orange to
magenta to purple to blue to black.
6.  Print the gradient using no Color Adjustment in the driver.
7.  Adjust the Selective Colors numbers to open up any flat areas in 
the
gradient.
8.  When you have a good gradient printing save the Selective Color 
options
and use it whenever you print.
Note - to "profile" this you will have to set the Grayscale Setup to 
Black
Ink Behavior then set the K channel in CMYK setup so that the on 
screen
*grayscale* gradient (pre RGB conversion) looks like the printed 
gradient.
Then for any new file you can adjust the grayscale file back to the 
proper
appearance, convert to RGB, add the saved Selective color setting 
(remember
that is with the mode set to "Color" not "Normal") and print with no 
color
adjustment.  (I think I put in all the correct steps here!).

The point of both methods above is to "Colorize" the grayscale file 
so that
it segments the ink values into the proper tonal zones.  Any method 
that
does that will work.  Avoid separating them so much that you are 
printing
single inks in any of the mid to dark zones - this causes banding.  
The
"huge" virtue of the CMYK method over the RGB method is that the CMYK 
Setup,
when properly profiled, give a much better preview than the Grayscale
preview.  If you can make a CMYK setup with a spectrophotometer, so 
much the
better.  The virtue of the RGB method is you don't need a special RIP
driver.

After all that -- might I recommend trying out Jon Cones Piezography 
BW
system - it segments the channels similar to the above superior CMYK 
process
but does it all automatically in the driver with profiles included 
for many
art papers.  Another option is the (still in beta) Spectrotone system 
from
Lincoln Inks and Papers (pipe in here Takichi).  It is designed to 
use the
RGB driver in a simplified process with a specially balanced inkset.  
Both
systems have strengths and weaknesses and print only on some and not 
other
papers - and neither is near as "fun" as learning the full CMYK 
process - or
even the RGB Selective Color method!

Dan

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