[Openicc] adding informations to ICC profiles

[Kai-Uwe Behrmann]

Am 23.11.05, 18:17 +1100 schrieb Graeme Gill:

> Kai-Uwe Behrmann wrote:
> 
> > in order to gather and store information about the device chain state
> > during calibration, I have written a proposal:
> > <http://www.oyranos.org/wiki/index.php?title=Device_Settings>
> > I like to attach device settings informations as text to existing
> > profiles.
> > 
> > Goal is to maintain ICC spec conformance. 
> > The technical easiest way would be an extra tag dedicated for
> > this purpose.
> > 
> > Is a device settings 'text' tag allready specified by ICC?
> > I only found an pdf containing a tag list, without enough further
> > informations about additional tags.
> 
> Most custom tags are undocumented.
> 
> Note that for some versions of the ICC spec. (V2.4), there is the
> "deviceSettingsTag", which was aimed at representing some of the
> types of information you are referring to. It seems to have
> been dropped from latter versions of the spec. though.
> 
> > Is it possible to take an existing profile and add a new 'text' tag, as
> > descibed above, without breaking any copyright?
> 
> I don't quite see where any problem would lie. To add another
> tag to a profile requires parsing it and re-writing it. To this,
> the software must preserve unknown tags (icclib won't do this
> currently, although it's on my "todo" list.)
> 
> I have come across another proposal similar in nature to
> what you are suggesting, but can't remember where I saw it.
> One of the comments I remember was that having a textural
> representation of settings is almost useless, since there
> is then no sure-fire way of systems recognizing the settings -
> you're just left with heuristics. Specifying a formal
> way of recording configuration that is flexible
> enough to cope with existing and future printing systems
> is daunting though. (The "deviceSettingsTag" is complex
> and not fully documented, and it probably doesn't cover
> everything.)

Hmm, it is probably difficult to do it in a centralised place like a CMS 
(still do not know how to distinguish between argyll and oyranos - booth 
are CMS?).

My idea is to take a whatever text blob from the device driver and embedd 
into the profile and give it back to the device driver to convert back to 
device settings by the driver itself. The idea came me by looking how 
Gutenprint stores its settings.
Thus a driver can write an short identifier only, compress (ok that would 
be a 'data' tag), xml-ise or use a native format like Gutenprint does.

regards
Kai-Uwe Behrmann
                                + development for color management 
                                + imaging / panoramas
                                + email: ku.b at gmx.de
                                + http://www.behrmann.name