[argyllcms] Re: Black Point Compensation

  • From: Gerhard Fürnkranz <nospam456@xxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 07 Oct 2013 23:24:18 +0200

Well, the BPC algorithm is at least well defined and documented, so any CMM 
could reimplement it.

On the other hand, ICC perceptual intent is not defined mathematically, but 
depends on the individual profiler implementation...

-Gerhard



edmund ronald <edmundronald@xxxxxxxxx> schrieb:
>bpc is yet another way to guarantee that every implementation of ICC
>will convey different results.
>
>Edmund
>
>On Sat, Oct 5, 2013 at 7:05 PM, Gerhard Fürnkranz <nospam456@xxxxxx>
>wrote:
>> BPC is normally not included in the profile, but computed by the CMM
>on the
>> fly when it applies the profile.
>>
>> -tla (luminance matched appearance) is possibly the most similar
>Argyll
>> intent which you can put into the perceptual table (though still not
>exactly
>> the same)
>>
>> -Gerhard
>>
>>
>>
>>
>> Joe Tschudi <tresorjoe@xxxxxxxxx> schrieb:
>>>
>>> Hello Graeme, Kai-Uwe
>>>
>>>>> BPC is now much in the heads of users. What is the equivalent to
>BPC in
>>>>> Argyll?
>>>>
>>>>
>>>> Use a real perceptual gamut mapping - ie. either create the output
>ICC
>>>> profile
>>>> perceptual table for the specific input colorspace, or create
>>>> a device link of the same transform. See
>>>> <http://www.argyllcms.com/doc/CrushedDisplyBlacks.html>
>>>
>>>
>>> Would that theoretically mean that using -S AdobeRGB1998.icc in
>colprof
>>> should deliver the same result for:
>>> 1) Conversions using Relative + BPC
>>> 2) Conversions using Perceptual
>>> (for example converted in Photoshop using Adobe (ACE) with
>selectable
>>> Black Point Compensation)
>>>
>>> I don't get the same result, what kind of -T parameter could give me
>the
>>> same conversion result in Perceptual as a Relative + BPC conversion,
>if
>>> there is any?
>>>
>>> Best regards,
>>> Joe Tschudi

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