Re: evaluating identical media in incorrect lighting conditions
Re: evaluating identical media in incorrect lighting conditions
- Subject: Re: evaluating identical media in incorrect lighting conditions
- From: Graeme Gill <email@hidden>
- Date: Thu, 29 Jan 2004 21:34:10 +1100
- Organization: Color Technology Solutions Pty. Ltd.
Steve Upton wrote:
Just to settle my(our) curiosity I did some color-shift calculations to see what kind of color
> differences we might see. Using the Atkinson 9.18 RGB target printed on an Epson 2200 and read
> spectrally I converted to 2 deg D50 Lab and to 10 deg D50 Lab. The difference between the files
>is significant. Most of the color shifts occur in the saturated blues and dark blues. The results are:
You want to be a bit careful mixing and matching observers. There is an arbitrary
factor in creating such curves, such that they can be used to verify a colorimetric
match, but don't use the same numbers to represent the same color. Unless
an alternative observer has been "tuned" for some sort of maximum compatibility
with the 1932 standard 2 degree observer, it's best to use the same observer
for creating both profiles in a link. I get the impression that the 10 degree
observer isn't a bad match for the 2 degree one, but it may not be perfect,
since (I think), it's arbitrary parameter was set to match just the Y to that
of the 2 degree observer, not to minimize its overall differences.
Graeme Gill.
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