[argyllcms] Re: Profile input white not mapping to output white

  • From: Gerhard Fuernkranz <nospam456@xxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Tue, 27 Nov 2012 17:04:29 +0100

Am 27.11.2012 16:52, schrieb Gerhard Fuernkranz:
Am 27.11.2012 14:56, schrieb Ben Goren:
Let me know if there's anything else I can do to help...but also let me again 
emphasize that, whether it *should* or not, adding D50 white to the .ti3 makes 
colprof work *exactly* the way it should.

Ben, if you like, then you could basically add a fake patch for RGB [1,1,1], 
but IMO the XYZ numbers of this fake patch should be at least consistent with 
all the other readings in your .ti3 file (within the errror margins).

I.e. the question is: Which (absolute) XYZ color would the patch need to have, 
in order that camera + raw converter would return non-clipped RGB of [1,1,1] ?

These are the XYZ numbers then, which you put into the WHT row.

Estimating the XYZ for instance with an -aG matrix model gives me:

   colprof -aG TrumpetChart-aG     (original .ti3 w/o fake patches)

   xicclu -ia -ff -px TrumpetChart-aG.icc
   1 1 1
   1.000000 1.000000 1.000000 [RGB] -> MatrixFwd -> 1.026545 1.052019 0.889471 
[XYZ]

which would lead us to

   WHT 102.6545 105.2019 88.9471 100 100 100 0 0 0

Best Regards,
Gerhard


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