[Openicc] ICC meta Tag for Monitor Profiles
Chris Murphy
lists at colorremedies.com
Thu Dec 2 06:22:39 PST 2010
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.
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.
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.
Chris Murphy
On Dec 1, 2010, at 2:32 AM, Kai-Uwe Behrmann wrote:
> The Draft provides means to embed monitor informations into ICC profiles.
>
> == Introduction ==
> ICC profile vendors have to maintain different installation procedures to
> register ICC device profiles on a client machine. This is either fully
> customised, but only for certain operating systems, or an manual error prone task through the required user interaction. With ICC profiles for monitors containing device informations, it will be easy for colour management systems to identify monitors and use a matching ICC profile without special registration in the system. This allows for easy preselection and implicit configuration. The advantage for vendors are less maintainance costs and better cross platform support in a flexible manner. Users benefit by the implementation of this proposal through a simplified and more robust colour management system. Adding of device informations to ICC profiles can be assisted through according tools.
>
> This proposal defines key/value pairs for storing into a ICC display
> profiles meta tag. Consequently only colour management and device
> identification related properties are considered for inclusion.
> A explicit configuration in a given CMS shall override such implicit
> mechanisms as defined by this proposal.
>
>
> ==Definition==
> The following key/value pairs are defined
> * (key: value)
> * EDID_mnft: decoded three byte string from EDID address 8-9
> * EDID_manufacturer: mapping of mnft to a full string - only for displaying
> * EDID_mnft_id: MSB decoded numerical representation of EDID address 8-9
> * EDID_model_id: LSB decoded numerical representation of EDID address 10-11
> * EDID_date: decoded year of production from EDID address 17
> and week of production from EDID address 16
> * EDID_primary_red_x:
> * EDID_primary_red_y:
> * EDID_primary_green_x:
> * EDID_primary_green_y:
> * EDID_primary_blue_x:
> * EDID_primary_blue_y:
> * EDID_primary_white_x:
> * EDID_primary_white_y:
> * EDID_gamma:
> The EDID_primary_ prefixed keys and EDID_gamma contain floats with decimal
> point. The values are decoded from EDID address 25-34 (colou primaries) plus address 23 (gamma)
> * EDID_model: decoded string from EDID text section 54 till 125 of typical type 252
> * EDID_serial: decoded string from EDID text section 54 till 125 of typical type 255
>
> Detailed instructions how to decode EDID can be obtained from VESA through
> the Enhanced Extended Display Identification Data Standard (E-EDID) - Rel. A, 1.0 .
>
>
> A parser must be prepared to interpret the contained values numerically and not always textual.
>
>
>
> ==Example==
> The data is a dump of iccDumpProfile from SampleICC
> Contents of metaDataTag tag ('meta' = 6D657461)
> Type: dictType
> BEGIN DICT_TAG
>
> BEGIN DICT_ENTRY
> Name=EDID_manufacturer
> Value=HP
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_mnft
> Value=HWP
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_model
> Value=HP LP2480zx
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_serial
> Value=3CM827001W
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_date
> Value=2008-W27
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_mnft_id
> Value=8944
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_model_id
> Value=9973
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_primary_red_x
> Value=0.69043
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_primary_red_y
> Value=0.296875
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_primary_green_x
> Value=0.205078
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_primary_green_y
> Value=0.714844
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_primary_blue_x
> Value=0.150391
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_primary_blue_y
> Value=0.0449219
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_primary_white_x
> Value=0.3125
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_primary_white_y
> Value=0.329102
> END DICT_ENTRY
>
> BEGIN DICT_ENTRY
> Name=EDID_gamma
> Value=2.2
> END DICT_ENTRY
>
> END DICT_TAG
>
>
> ==Discussion==
> A tag to embed the complete EDID data block is defined. But that serves
> different goals. Namely it is not possible to support a wider range of
> devices by this approach.
> To create a generic meta tag, the serial number and possibly production
> times need to be stripped from the meta tag, if they are considered non
> relevant in regards of colour rendering. Most monitors series will be well
> identified by the model_id and mnft_id entries. Others might need the
> colour_matrix_text_from_edid_redx_redy_greenx_greeny_bluex_bluey_whitex_whitey_gamma
> if they can switch colour spaces.
> The "week", "year", "mnft_id" and "model_id" keys might contain value
> ranges as allowed by the ICC meta tag definition.
>
>
>
> ==References==
> 1. ICC - http://www.color.org/
>
> 2. meta tag - http://www.color.org/ICCSpecRevision_25-02-10_dictType.pdf
>
> 3. VESA - http://www.vesa.org/
>
> 4. EDID - Enhanced Extended Display Identification Data Standard (E-EDID) - Rel. A, 1.0
>
> 4.1 http://en.wikipedia.org/wiki/EDID (overview)
>
> 5. ISO 8601 - Data elements and interchange formats – Information interchange – Representation of dates and times
>
>
> ==Changes==
> DRAFT 1 - initial
> DRAFT 2 - splitting of colorimetry compound, Richard Hughes
> - use EDID_ prefix, Max Derhack and Lars Borg
> - use ISO 8601 for dates, Lars Borg
>
>
> regards
> Kai-Uwe Behrmann
> --
> developing for colour management www.behrmann.name + www.oyranos.org
>
>
> PS: Further discussed could be the EDID CMD block. If someone would pass us a
> EDID block containing such data, that would be helpful. Thanks.
>
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