Re: Relative Shadow Density


--- In colortheory@y..., aaronkiley@y... wrote:

I have a question about "kinds" of black. (assuming all the
following would be light GCR)... Does a shadow made with
higher black
ink, (73c 63m 63y 91k) versus the same total ink shadow
made with
less black (80c 70m 70y 70k) have roughly the same look?
It would probably be image specific, with larger or more dense
areas of shadow appearing darker with the higher black sep. If
the shadow regions were quite small or had less contrasting
colours adjacent to them, then one may not notice the visual
density difference as much.

Both mixes have the same amount of TAC/TIL/TIC - 290%.

Since black ink in commercial flatsheet is so rich - there will
usually be a big difference between 70k or 90k.

It would probably be risky going to newsprint with 90k CMYK

If so, is
it increasing contrast in the black channel that makes a
shadow look
It is the higher total amount of black that produces this affect - the
contrast throughout the rest of the plate will be dependent on dot
gain and separation variables (and the image obviously).

I'm trying to reverse engineer some images that were
corrected by someone else. They have a very solid black "look"
a ton of shadow contrast. The only way I can get this look on
is a huge black contrast curve.
You could try separating in a false duped file - with a higher dot
gain lighter black generation or black limit, targeting the K
channel then using apply image to apply the K plate to itself in
multiply mode at whatever opactiy...then use a contrast
enhancing curve and or linear curve.

Even though there are very good reasons for keeping black lower
in shadow areas - clients always want more contrast.

Nothing adds contrast quicker than a rise in black ink.

I am working for a smallish printer, and we commonly separate
anywhere around 320-360% limits with high CMYK shadow
values (see a recent previous post from me on the UCR, GCR or
OFF? thread).

This is for coated stock on a flatsheet offset litho press (Fuji 5

Before working here, I considered such settings too optimistic -
and they are for some images...but for quite a number of our
jobs - this 'technical mud' is very pleasing to clients. Sadly,
clients don't care about standards or specifications - they just
want more contrast and better colour. <g>

If a sep had a shadow under 80c 70my 70-80k, then I would
probably fix it (if appropriate for the image and job brief).

If the values were higher, but different - but still acceptable, then I
would probably equalize them to a value around the original -
either higher or lower depending on the content and output.

This is my general approach, for what it's worth.

Hope this helps,

Stephen Marsh.

Join { to automatically receive all group messages.