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

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sun, 25 Nov 2012 11:12:15 +1100

Ben Goren wrote:

> EUREKA!
> 
> Based on this, I added the following two lines to the .ti3:
> 
> ZZ1 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.00000 0.00000 0.00000 ZZ1 
> 96.4220
> 100.00 82.5210 100.00 100.00 100.00 0.00000 0.00000 0.00000

> Is there any chance this behavior could get added as a switch to colprof? 
> Perhaps -uc,

Hi,
        no, I can't put something like that in the code, because
it is making very strong assumptions about the device behaviour.
That's simply wrong in general. Nothing should be assumed about
the device except what is indicated by the sample values.

-u makes more justified assumptions, since the extra points are from
a model based on the actual data. If you turn on verbose it will actually
print these extra values out "Added synthetic point @..."

> for ``input from a camera,'' and with a description along the lines of 
> ``force input
> pure black and white to output pure black and white''?

How do you know what is "pure" white and black input, without making
assumptions about the device ? If the device has (say) an offset
on a channel, black won't be 0. If it is color balanced to
a different white point, white 1,1,1 won't be D50.
If a channel saturates or clips below 1, white won't be 1,1,1.

Graeme Gill.

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