[argyllcms] Re: Large whitepoint difference
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 11 Sep 2007 17:09:00 +1000
John Weissberg wrote:
I have noticed a very large difference in the whitepoint actually
measured (the 0 0 0 0 point in the .ti3 file) and the whitepoint stored
in the 'wtpt' tag in a profile generated by Argyll.
Measured whitepoint (from .ti3 file): 97.510 0.78000 -2.9600
Whitepoint from wtpt tag: 89.079722, 0.552168, -2.911983
The difference seems huge to me. Can someone explain how it may have
come about?
I think the data set is basically inconsistent.
For instance, take a look at these three values:
1: 0.0000 0.0000 0.0000 0.0000 -> 97.510000 0.780000 -2.960000
3106: 1.0000 1.0000 0.0000 0.0000 -> 87.580000 0.970000 -4.000000
3097: 2.1800 2.2000 5.2000 0.2000 -> 93.070000 -0.510000 3.910000
So this is saying that adding an additional 1% Cyan, 1% Magenta, 5% Yellow and
0.2% black
to 1% Cyan and 1% magenta makes the result 6 delta E lighter !
The data set is full of similar contradictions, hence the poor
profile fit, no matter what resolution table is used.
There's either an issue with device or instrument consistency, or the
devices behaviour is highly non-monotonic.
Graeme Gill.
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