Re: not quite neutral grays
Re: not quite neutral grays
- Subject: Re: not quite neutral grays
- From: bruce fraser <email@hidden>
- Date: Wed, 24 Mar 2004 08:26:48 -0800
By 'Dead-nuts neutral" I meant that the neutrals measured with a* and
b* values within 0.1 of 0, so the point of view was that of the
Spectroscan.
Basically, we adapt to paper white and judge all other colors in that
context. My experience has been that a really neutral neutral from,
for example, the Fuji Pictrography, looks yellow, while a neutral
that measures a little cold looks OK.
Gretag software offers an option called Paper Gray Axis, that biases
the neutrals relative to the paper color. I find it very useful...
Bruce
At 7:50 AM -0500 3/24/04, Roger Breton wrote:
> It depends on the paper...
With distinctly blue-white papers that contain optical brighteners, a
dead-nuts neutral appears yellow. With distinctly yellowish papers, a
dead-nuts neutral appears blue.
Aha! The infamous 'dead-nuts' color. I'm sure Marco would not approve of the
terminology... But, just to be clear, 'dead-nuts neutral', ok, but relative
to what? Because if something appears yellow or blue on a paper it is then
'dead-nuts' relative to the paper? You must be refering a color where a = 0
and b = 0 in Photoshop. For example, start in Lab with a value equal to
50,0,0 and convert that value, RelCol, to some printer profile. Print. You
say this printed color is supposed to come out 'dea-nuts neutral'? Or do you
simply mean make the color such that it will appear the same shade or hue as
the paper color itself once printed? Which would mean, perhaps, AbsCol from
Lab? Example: if the paper is L96 a -1 b -4 and I can mix a color that
produces L70 a -1 b -4 on output, would you regard that color as 'dead-nuts
neutral'?
It seems to depend on your point of view...
You'll have to provide for an absolute, non-equivocal definition of
'dead-nuts neutral', Bruce. Give my poor melted brain a chance.
Unless you mean 'appearing' yellow in the sense of a gray patch measuring
'dead-nuts' a=0 b=0 in D50/2 on some distinctly blue-white papers that
contain optical brighteners, will appear *yellow* because of an optical
phenomenon called simultaneous contrast. And vice-versa.
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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