Re: GaMapICC v0.5
Re: GaMapICC v0.5
- Subject: Re: GaMapICC v0.5
- From: Graeme Gill <email@hidden>
- Date: Thu, 28 Jan 2010 17:15:49 +1100
Marco Ugolini wrote:
What "original"? The AdobeRGB image file, which only exists in electronic
format?
Actually, the AdobeRGB standard specifies a set of viewing conditions
e.g.:
"The luminance level of white displayed on the reference color monitor
shall be 160.00 cd/m2"
"When measured, with the monitor turned off, at the monitor faceplate,
the ambient illumination level shall be equal to 32 lx."
"Reference Display Surround" ..
"Its luminance shall be 20% of the reference display white point, that
is, 32.00 cd/m2."
etc.
So there is enough in "AdobeRGB" to infer a pretty definite appearance,
quite apart from the practical one of a typical display setup.
What happened to standard viewing conditions in a color-correct (D50)
viewing booth of standard illuminance? Now we must be converting for CIECAM
too? This is getting stranger and stranger.
CIE values are defined under a fairly rigid set of viewing conditions.
Real world viewing conditions vary quite substantially from the CIE
conditions, and a Color Appearance model gives us a tool to attempt to
maintain appearance across different display technology and
different viewing conditions.
A good thing only if one doesn't work in imaging production, and can afford
endless theoretical speculations in place of producing viable results. I
can't imagine how one would ever get anything done, when one throws a
million variables at the problem, each of which changes everything.
Hmm. I'm not sure how much more un-theoretical you can get
when there are tools to do the job, and we're comparing real raster files.
If you want you can measure and set exact viewing condition value, but in
practice choosing from a set of typical pre-sets seems to take you a good
way there.
Graeme Gill.
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