Image sharpening vs. plate sharpening -- Was: Scanning old postcard for use on book cover

["Preston Earle" <PEarle@xxxxxxxxxxxx>]

"Arthur Entlich" <artistic-1@shaw.ca> wrote:
"I am using these terms in a more modern sense than perhaps you would
interpret them.  As you are very likely aware, today the "plate making"
(if a plate even is used, as such) is often done directly from digital
files with no intermediary film steps. Even as I was typing the phrase,
I was thinking "someone in the printing profession is going to complain
about this", but I also decided I didn't wish to go into the
detail...)."
------------------------

I don't mean to quibble about semantics and would let this subject go,
except for the impression that you have left that printers can "sharpen"
images in the platemaking process.

I believe you are confusing two different concepts which use the same
word. Image sharpening (aka USM) is the enhancement of apparent image
sharpness by increasing edge contrast within the image. Plate
sharpening, OTOH, refers to dots on one plate being "sharper" than dots
on another plate and thus (usually) printing lighter. Typically, plates
made by CTP processes are "sharper" than "conventional" plates made from
imaged film. In order for the CTP plates to match the conventional
plates, the mid-tone dot sizes are adjusted in the CTP plate-imaging RIP
to give the same print densities as the film-based dots. This has
nothing to do with image sharpening.

Printers generally endeavor to duplicate the files they are given. If a
printer has a long-standing relationship with a particular customer, the
printer may "improve" furnished files by color-correcting or enhancing
sharpness. Absent other instructions, the printer is generally going to
give the customer just what is in the files. The files should be
properly sharpened before submission to the printer.

I'm not a pressman (and despise the nickname "Press"<G>). I have owned a
very nice printing company, including an Indigo press, but that is
another story.

Preston Earle
PEarle@triad.rr.com


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