[argyllcms] Re: How do I measure individual patches on my display?

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sun, 08 Mar 2009 12:36:32 +1100

Leonard Evens wrote:

I just tried it again with the -d and -yl options but left out -N.  This
time the L readings seemed to make sense.

Hmm. I'm not able to reproduce this problem with my current code, in
which -N works as expected again.

There is still one thing I don't understand.  I thought L was supposed
to range from 0 to 100.  My highest reading was over 105.

It has a value of 100 when it reaches "white". You have to establish
a white though, and emissive and display measurements are absolute
in cd/m^2, so the L*a*b* conversion "white" value is taken simply 100 cd/m^2.
If you use -db or -dw you get to set an actual white value, and both
the XYZ and L*a*b* readings are normalized to 100.

Graeme Gill.

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