Re: Gray Balance and Rip Linearization
Re: Gray Balance and Rip Linearization
- Subject: Re: Gray Balance and Rip Linearization
- From: Roger Breton <email@hidden>
- Date: Sun, 28 Nov 2004 20:27:45 -0500
> My question is first off what is a good cmyk reference file to print to
> check how well my gray balance is. I have seen different cmyk gray scale
> test files but they all have different cmyk values on what is gray. I.e..
> C50m m40, y40 K20 or something like that. With that being said, even if gray
> balance is off a little bit, wouldn't my printer profile correct for this?
> In this case I am using Print Open 5 to generate my printer profiles.
> I assume the better I get best to output a good gray scale would be best but
> I am not sure.
>
> Kornreich Fine Art Prints
> Steven Kornreich
This whole business of gray balance is very dear to my heart. What is gray?
And do we judge gray? Relative to what?
I suggest there are two ways of approaching gray. The first is an "absolute"
way, using some Illuminant as a reference. Thus if, through measurement, I
determine some surface or light to yield chromaticities equal to the
Illuminant I use as my gray reference, such as D50, then I don't believe I
have any other choice but to conclude that I am in the presence of a gray
sample. Logical. So, you see, in this approach, gray is gray but only
relative to a certain Illuminant or white reference. If I use D50 in my work
and I measure my injket proofs grays to yield D50 chromaticities then I have
to conclude that my proofs are neutral.
The second approach, as far as proofing is concerned, is to formulate grays
relative to the substrate itself. So, for instance, if the substrate is L94
a-1 b-4, typical of Fuju Fpsatin in Canada, then if the grays I achieve on
this paper have the same a and b value (or the same chromaticies as the
unprinted paper) as those, irregardlessof the L value, I have to conclude I
have reach grays and leave it at that.
Being very concerned with this idea of grays, I once purchase some Munsell
Gray scales and some Natural Color System gray samples.
Of course, a good profiling package like PrintOpen will be able to come up
with balanced grays for the paper and ink at hand. But it's possible that
there is a difference between PrintOpen's internal model and the actual inks
behavior. In which case, you have no choice but to edit the gray balance of
the profile. But, first, do check what the profile is giving you, in
absolute colorimetric intent before you jump to conclusions.
Regards,
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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