Re: Header white point is not D50?
Re: Header white point is not D50?
- Subject: Re: Header white point is not D50?
- From: Steve Upton <email@hidden>
- Date: Tue, 16 Dec 2003 11:42:03 -0800
At 10:15 AM -0800 12/16/03, Doug Walker wrote:
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While repairing Profiles with ColorSync Utility I notice many have the following notation:
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Header white point is not D50. Fixed.
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I should have only Verified, right? Before selectively repairing?
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Was this global repair not a wise and good thing to do if my workflow is 6500?
There are typically two white points specified in a profile.
The white point in the header refers to the white point of the Profile Connection Space (PCS). As the ICC has specified that the PCS white point is D50, then any profile that has a white point in the header other than D50 (or D50 encoded incorrectly) needs to be corrected - no questions asked.
The white point that a display may be calibrated to can obviously be different than D50. This is encoded in the 'wtpt' tag.
Now, in version 4 ICC profiles 'wtpt' tags need to be adapted to D50 so even a 6500K-calibrated display will have D50 in the 'wtpt' tag. This is going to cause some confusion.. Where should the calibration point of the display be recorded in the profile? in the viewing conditions tag. Whether or not this happens correctly in the future remains to be seen.
And yes, for those thinking this to the next step, Adobe RGB and sRGB should both have D50 as their 'wtpt' in v4 ICC profiles. Did I say confusion?
Regards,
Steve
________________________________________________________________________
o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX
o email@hidden 206.985.6837
o ColorGear ColorThink ColorValet ColorSmarts ProfileCentral
________________________________________________________________________
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