Quadtone success (qualified)

["Doug Kelly" <kdouglas1@uswest.net>]

I'm just about bald from tearing my hair out, but I think I'm finally
closing in on successful quadtones with my 740. Many thanks to all on the
list - some I've managed to respond to and thank, some not (just reading the
traffic takes a whole lot of time, let alone responding).  My method is a
hybrid of Dan's RGB approach and the custom separation process Strange
posted a while ago, although I kinda butchered them along the way.

What I ultimately did was take the purge4.tif file from MIS (just solid bars
of C, M, Y and K), and throw a gradient screen over them (0-100%). I then
printed this, and scanned the result.  A bit of inspection and blurring of
the resulting image allowed me to visually select the most linear portions
of each ink, and manually match them into a reasonable grescale ramp.  It's
still not perfect, given the almost unbelievably primitive curves editing
interface in Photoshop, but it looks to be _very_ close.  I still haven't
worked the 25% ink into the picture as much as I'd like, but the 50% does
remarkably well in the highlights.  There's no hope of accurate visual
preview, and I'm simply using linear segments for each ink (no overlap
between inks) for now. (and even that was hard enough to tweak into a smooth
set of curves)

I'm printing on the recently-in-the-spotlight Heavyweight Matte paper, and I
quite like the results. Warm, but not overly so, and holds detail well.  I
find that the 100% black ink seems to give better blacks than on any of the
other papers I've tried.

With regards to the curve editing issue - is this just my lack of knowledge
of photoshop?  I realize that 99% of the time, the curves tool is used in
line/smooth mode, but for manual seps you have to use the pencil mode.  Are
there ways to zoom or magnify that I don't know about?  Barring that, is
there any other way to generate the curves?  A plug-in or documented file
format?  At the moment, I'm thinking that simply writing a program to read
in a greyscale tiff and spit out an RGB tiff might be the easiest
approach.....

Once again, thanks to all fellow quadtoners for the advice picked up.

Doug Kelly

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