Re: Sony Artisan 1.2 Colorspaces Question
Re: Sony Artisan 1.2 Colorspaces Question
- Subject: Re: Sony Artisan 1.2 Colorspaces Question
- From: Roger Breton <email@hidden>
- Date: Tue, 02 Sep 2003 09:56:27 -0400
>
> I find when I measure some characterization target under a 1000W quartz
>
> halogen lamp with a Minolta 1 degree Luminance meter:
>
>
>
> 350% CMYK 136 Cd/m2
>
> White stock 367 Cd/m2
>
>
>
> As you can see, that's not a very big contrast ratio of 2.69! If I measure
>
> under a dimmer light like a Solux 50W 35degree 4700K lamp at 8 feet from
>
the
>
> printed sheet I get:
>
>
>
> 350% CMYK 2 Cd/m2
>
> White stock 42 Cd/m2
>
>
>
> Or a contrast ratio of 21.
Bertho,
>
The first number looks way too low which you noted too. Any chance that you
>
picked up a specular reflection on that measurement?
To make the measurements, I took the time to mount the Luminance meter onto
a tripod and measured at normal angle of incidence relative to the press
sheet which I taped onto a wall at about 5 feet from the floor. No matter
how much I redo the measurement I got the same reading.
If instead I place my sample press sheet in my GTI D5000 viewing booth where
there is 3120 Lux illumination, I get:
White stock 650 Cd/m2
350% CMYK patch 40 Cd/m2
A ratio of 16.25 to 1. So, the amount of light falling on the sheet has an
effect on the contrast ratio. Si it seems that there are many interpretation
for the concept of "Contrast Ratio".
To me, if I want to compare apples with apples, as monitors are measured in
Luminance after all, then I don't see any other light metrics I should use
to carry on a meaningful comparison.
>
Not knowing better, should not the monitor be calibrated/profiled for
>
optimum performance and then let it alone?
I think that's what it boils down to. But it's important to remember that
the intended calibration is always relative to the PCS white point withch is
D50, the perfect reflecting diffuser. Otherwise, it's meaningless. There are
some new guidelines in v4 of the ICC specs, I think, which clarify the PCS
Viewing conditions but I have not had the chance to dig into them.
>
If a printer's limited range is
>
to be evaluated, should that not be done through the "Pre-view" function in
>
PhotoShop?
Absolutely. And for the most accurate comparison this should be done with
Simulate Paper White turned on, as I gather from a paper published at this
year's TAGA by Abhay Sharma that this setting yields the best colorimetric
performance in softproofing.
>
By the way, the paint winner was Behr 1050.
Do you have more info on this paint?
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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