Re: Photopolymer Optimization of letterforms
I'm glad you like the proofs. In response to your questions:
> Is the -.064 choke normative or maximum?The -.064 choke is neither normative nor maximum. It just happens to
be what gave the best overall effect for that particular test page.
For best results I think you should apply less choke to smaller sizes
of type, and more to the larger, and it bears some experimentation
with the amounts applied to different typefaces. I found that
the "gain" from my laser printer (relative to the high resolution of
an imagesetter) roughly mimics the gain from letterpress, and it is
therefore possible to experiment first with laser proofs before
wasting a lot of expensive film and plate material.
> How much further could you choke before you experience letterformThe amount of additional choke that can be applied depends both on
the specific typeface design, and on the size at which you are
reproducing it. Smaller types, and those with finer lines, will start
to break up before the larger sizes and heavier designs. Quark allows
a choke of up to -36 points---three whole picas!---which is obviously
far more latitude than we need for this purpose. In most cases I
would think an appropriate amount of choke for a text face would be
between -0.100 and -.008 points, depending on the size and the design.
> I assume this is possible in PageMaker, Illustrator, InDesign asI do not have first-hand experience in trapping/choking with these
> well, do you know?
programs, but they undoubtedly must all have some sort of function
for addressing trapping of colors to one another. If so, they can
probably be adapted to choke the text the same way that it works in
> Does this effect leading or other page parameters; line length,The choking/trapping does not have any significant effect on line
> text block measure, etc?
length or text block size. It basically is just the reverse of the
gain that you get from ink squeeze on press.
> What are the difficulties encountered in explaining the trapping toThe problem that I encountered with one film house was just in trying
> the folks at the service bureau (film house)?
to make it clear to them what I wanted the final output to look like.
It can be confusing because what you need is positive film of the
colored background (this is what has the choked type knocked out of
it), which will end up looking kind of like a negative piece of film.
And of course, the film also needs to be right-reading/emulsion-up.
For most service bureaus it should not be a problem if you ask them
for RREU Positive film of the color channel. If they are outputting a
file that you prepared yourself, they should not need to do anything
with regard to the trapping/choking. (Note that you do not want film
for the black channel, even though this is technically the channel
with the type in it.)
I hope this is making some sense to everyone. It is much easier for
me to explain in person, where I can draw diagrams and use hand
gestures. I will gladly try to answer more questions if you have them.
With best regards,