Re: G7 press calibration, best press conditions or average?
Re: G7 press calibration, best press conditions or average?
- Subject: Re: G7 press calibration, best press conditions or average?
- From: Mike Strickler <email@hidden>
- Date: Sun, 9 Nov 2008 20:37:58 -0800
Hi Henry,
Several topics seem to have gotten conflated here. The question of
the specialness of the G7 method has gotten tangled up with the
question of the superiority of colorimetric methods, of which G7 is a
subset. There is also the question of when and by whom G7 might be
used. Separately:
Densitometry is fine for process control, as has been stated, but
pretty crummy for setting standards, as it doesn't dependably predict
color appearance regardless of the sort of ink or toner used, as
does L*a*b*, for example, which is inherently a measure of
appearance. Where a system is already within ISO specs (ink, paper
type/color) density specs already exist, and one could get by
calibrating with a densitometer. That one can get by in certain
situations is no reason to recommend it for general work. A trivial
but common example of a shortcoming of densitometry is in adjusting
for paper color. Even if you print to published specs (SWOP, Fogra
28, whatever) but use a paper of a different color (and who doesn't?)
you must proportionally adjust the aim points of "neutral" CMY
patches to toward the color of the paper, or the result will appear
color-casted. With a spectro this is child's play, whereas with only
a densitometer it is an indirect process at best. It is strange that
people who accept and use colorimetry in the form of ICC profiles in
every other area of color control would argue against it when it
comes to this one particular output device, the offset press. It was
one thing when spectrophotometers were simply too costly, but now?
I don't particularly want pressmen worrying about L*a*b*. It's best
to determine the densitometric aim points for their press and
substrate and have them stick to them.
G7 in particular: It's logical, straightforward, and fast (if one has
the Idealink software). It's also flexible, easily allowing one to
get the same ISO gray balance and very similar overall color
appearance with different ink sets on different substrates, with
systems of varying color capabilities and behaviors. What's not to like?
Mike Strickler
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden