[Openicc] ICC meta Tag for Monitor Profiles

Kai-Uwe Behrmann ku.b at gmx.de
Thu Dec 2 06:49:32 PST 2010

Am 02.12.10, 07:22 -0700 schrieb Chris Murphy:
> I am curious about the actual usage case with examples so I can better
  understand the purpose of this meta tag, in particular in the context of
  the generic meta tag need.

The Oyranos monitor utility is able to embed device identification strings 
with the help of the meta tag into ICC profiles. These profiles
appear on the upper rows in the list of selectable ICC profiles for a 
device in kolor-manager. Further Oyranos can implicitely select an ICC 
profile by this tag if none is explicitely assigned for the given device.

> My gut reaction to a device serial number is that it should not be
  stripped because that could be useful in automating the pairing between
  profile and display so that users don't have to do this. During
  production, displays do change behavior, even if the manufacturer and
  model stay the same. So I question the value of a profile with a generic
  meta tag, which is why I'm asking for a usage case scenario.

In case a monitor is know to keep the EDID information up to date, e.g. 
adapt the primaries to compensate aging and maintains a good linearity to 
the EDID claimed gamma value, then a canned profile will perform 
comparably badly and should better be avoided.

However, for most of our current displays the meta tag is the right tool
to fix monitors with broken EDID, I have seen recently one with gamma 1.0 
and provide a better result than a from EDID generated ICC profile.

A canned ICC profile with meta tag can do more for monitors with far 
away of any linearity, than a pure on the fly from EDID generated profile.

> If the scenario is this notion of downloading ICC profiles for a
  make/model of display, I think this has pretty much proven to be just
  short of a disaster. I don't think display profiles should be made
  available for downloading from a web site, or in an system/driver update.
  Ever. Manufacturers have regularly shown complete disregard for basic
  requirements in building valid ICC profiles for their displays. I think
  it's better to insist that EDID data be, a.) correct, and b.) upon
  connection to a computer, the automatic creation of an ICC profile to
  occur, and the relevant EDID data to be embedded in that ICC profile.

Well, they can learn about the new tags usage, as they needed to learn 
other installation routines in the past.

At least distributors will be able to package ICC profiles and provide 
magical better colour correction. For some users this can come out of the 

> Chris Murphy

kind regards
Kai-Uwe Behrmann
developing for colour management 
www.behrmann.name + www.oyranos.org

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