[argyllcms] Re: Fakeread with cmyk profile...

  • From: "Auke Nauta" <auke@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 20 Feb 2009 08:46:25 +0100 (CET)

Dear Graeme,

> My guess is that the profile has no black point tag, so the ICC default
> of 0,0,0 is used instead. Since you've set a black target of 0,0,0,
> nothing
> changes.

That was it. Thanks!
Just added the tag myself and all is fine in CMYK world again ;)

Best regards,
Auke


> Auke Nauta wrote:
>> I do not have any chart readings of this profile, nor are they embedded.
>> The actual blackpoint of the device is approximately 10.5,1.5,1.0 (Lab).
>
> Right. Does the profile have a black point tag that has this value
> in it ?
>
>> So I use:
>> * targen -s17 -g33 -e8 -d4 -f4092 -I -cMy_CMYK_Profile.icc target (.ti1)
>> * fakeread -l -b0,0,0 My_CMYK_Profile.icc target (.ti3).
>> * colprof -v target (.icm).
>>
>> Now the thing is that *some* scaling is going on depending on the -b
>> parameter during fakeread, but the actual blackpoint is *never* lower
>> than
>> the initial 10.5.
>>
>> I'm at a loss here!
>
> My guess is that the profile has no black point tag, so the ICC default
> of 0,0,0 is used instead. Since you've set a black target of 0,0,0,
> nothing
> changes.
>
> [ The next release will take a somewhat smarter approach, and determine a
>    black point if the profile is missing the black point tag. ]
>
> Graeme Gill.
>


-- 
In a world without walls and fences, who needs Windows and Gates?


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