Re: Sony Artisan 1.2 Colorspaces Question
Re: Sony Artisan 1.2 Colorspaces Question
- Subject: Re: Sony Artisan 1.2 Colorspaces Question
- From: Andrew Rodney <email@hidden>
- Date: Thu, 04 Sep 2003 13:59:29 -0600
Here9s some information I got in regard to this question about Artisan and
contrast ratios (measuring with an external device):
Measuring contrast ratio is a complicated subject. Pointing a spot
luminance meter at a sample of black and white - or at your screen -
will not provide useful data. Contrast ratio is effected by flare,
gloss, measurement geometry, target geometry, backscatter,
polarization, light scattering in the eye and many psycho-physical
factors as well.
Complex measurement procedures have been developed and standardized by
ISO and ANSI. Most of these are not comparable to each other. You can't
really use the ANSI LCD contrast measurement method and compare it to
to the ANSI CRT measurement or print measurement method.
Current research, and standards that are on the way, do allow you to
translate some of this apparent difference between media types.
Appearance models such as CIECAM2002 can translate between media of
differing apparent contrast ratios. CIE LAB and hence ICC color
management does not do this.
The contrast ratio definition used by the Artisan software is called
"Absolute Contrast Ratio." The entire background is set to a fixed grey
value and the sample patch of a fixed size ratio is measured at White
and Black. The method of measurement is not important, our ability to
accurately reproduce the requested contrast ratio is.
Since the ICC does not support contrast ratio media translation (screen
to print) we have added colorspace choices so the display softproof
will more accurately reflect the print. It is important to note that
their will be no difference between the ICC profiles produced by say
"Print RGB 1.8 D65 300:1" and "Fine Art RGB D65 500:1" Both have the
same RGB Phosphors, the same TRC, and the same White Point.
To be able to utilize the darker contrast ratio choices you must be in
a dark environment. The amount of light reflected off the face of the
CRT must be less than half the black luminance. This means that the
room diffuse illuminant should be less than 8 lux for 400:1 and 4 Lux
for 500:1.
Choosing a value between the three settings that we provide
(500,400,300) is most likely splitting a hair that does not need to be
split. If however your are printing on newspaper or some other form of
blotter paper ;-) you may want to try setting it to less than 300:1.
It is correct that the environmental illuminant should match the
display white point. Mixed mode adaption is also not yet part of ICC
color management.
Hope this helps.
Andrew Rodney
http://www.imagingrevue.com/
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