Re: Is anyone printing QuadTones?

[Dan Culbertson <danculb@concentric.net>]

John Kantor  wrote:
>I was wondering if anyone has experience printing quadtones using MIS
>Supply inks
>or similar.

Yep, loads of experience.  Work great when you segregate the channels by
tone range -- work okay when you just print as a grayscale to the color ink
in the regualr driver.

To segregate the channels you have to duplicate the grayscale file three
times in the channels pallette then convert the resulting four channel
"Multichannel" mode to CMYK.  Then apply a set of curves that focuses each
channel on the range it's ink (25%, 50%. 75%, and 100%) will accomodate
best.  You will have to set the printing inks set-up colors in CMYK setup
to get a grayscale emulation on your monitor.  The best way to print is
through a RIP which allows control of each ink head.  But you can do a
workaround by converting the CMYK file to Multichannel, then converting it
to RGB, then clicking on the "Black" channel (now a spot channel in
Photoshop 5) and setting the solidity to 100%, then printing through the
RGB driver with "No Color Correction."  The interim conversion from CMYK to
Multichannel is critical - do not convert directly from CMYK to RGB.  I
have posted my procedure for isolating each channel at
http://www.geocities.com/~campfiredan/infoshare/quadinst.html
Note that it is a rather difficult procedure but it is based on some very
conventional methods for printing with unusual inks like quadtones.  You
will need to do a lot of iteration and trial and error when coming up with
a set of curves and Channel Mixer adjustments to accomodate your type of
image.  My settings are just starting points. The big "secret" here is to
limit the total ink to well under 200% while still getting full blacks.
That is why I use the Channel Mixer adjustment -- to remove extra light ink
in the dark areas.  There are other ways as well.  Also note that the
printing inks setups I've listed are for the four color printers.  MIS has
assigned the inks to different cartridges for the six color printers and
this method will not work well with those ink assignments.  To use this
with the six color printers you would have to put the 25% ink in the Cyan
and Light Cyan, the 50% ink in the Yellow, the 75% ink in the Magenta and
Light Magenta, and the 100% in the Black cartridges.

The other method is to just print a grayscale file to the standard Epson
driver.  This does not keep the dark inks out of the light tones, but the
result is a neutral gray across the entire grayscale.  This method will
probably work a lot better with the new variable dot size printers but with
standard printers you can get some pretty heavy black dots in the highlight
areas which can ruin some images.  You might try this method first (select
Vivid in the driver and adjust the sliders to whatever works best).  You
might also convert the grayscale to RGB and adjust the RGB file so that you
have a very colorfull image with green/blue in the highlights
orange/browns in the midtones and magenta/blacks in the shadows.  This
somewhat partitions the inks like my more complex procedure but the control
is rather weak and you need a lot of guesswork and feel.  This is also
based on the four color printers ink assignments not six color printers.

Anyhow, any other questions, just ask!  They work well but are not really
simple to make work great.  You can get some pretty stunning "toned"
effects when you partition the channels correctly.

There are some other quadtone inks soon to come on the market which may be
as nice.

Dan Culbertson




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