U of S | Mailing List Archive | alt-photo-process-l | Re: photopolymer

Re: photopolymer

In a message dated 5/6/07 12:03:30 AM, erie@shelbyvilledesign.com writes:

IF they're using it properly, i.e. creating a stochastic screen function
and then just telling the imagesetter to output a box so many points
high by so many points wide, filled 80%, then the resolution is device
dependent, and is determined by the RIP, accounting for the matrix size
and rotation. For a 256 gray scale at 0 degrees (typically used), it's a
4x4 matrix, though the rotation, if used affects the matrix size.

There's a good explanation of Postscript halftones in the Postscript
reference books, I think the blue book, though it's been years (~20)
since I've written raw Postscript, so I may be mistaken. The reality is
likely that they're doing it from within a graphics program, and unless
they're intimately familiar with Postscript (and I've only met 3 or 4
people that care enough to be) the likelihood is the graphics software
is outputting a 600 ppi image (Illustrator, in particular is pretty bad
about this, since version 7, as I recall), as opposed to the code to
create a stochastic screen function at the raw imaging unit resolution.


Best Wishes,
Mark Nelson

Precision Digital Negatives - The System
PDNPrint Forum at Yahoo Groups

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