Re: colorsync profiles containing 'vcgt' tag
Re: colorsync profiles containing 'vcgt' tag
- Subject: Re: colorsync profiles containing 'vcgt' tag
- From: Neil Okamoto <email@hidden>
- Date: Fri, 26 Oct 2001 17:35:25 -0700 (PDT)
The ColorSync 2.5 documentation shows the 'vcgt' tag
has two flavors. Most profiles appear to store gamma
as a "formula" having min, max, and gamma parameters
for each channel. However it's also possible to store
gamma as a table of values. My tool uses the latter,
and this seems to fail on OS X. Forwarding to the
colorsync-dev list, perhaps someone there can help...
n
--- email@hidden wrote:
>
>
In a message dated 10/25/01 7:08:40 PM,
>
email@hidden writes:
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>We have some monitor calibration software that
>
exports
>
>monitor profiles containing a 'vcgt' tag. Under OS
>
9
>
>the gamma table is correctly installed when I set
>
this
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>profile as the default monitor profile. On a OSX
>
box
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>the profile doesn't seem to have any effect. Any
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>developers have advice how I can begin to debug
>
this?
>
>
This is the Video Card Gamma Tag, and contains the
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data downloaded to the
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RG&B channels of the video card to adjust the color.
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Older cards may not
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accept this type of download under Windows, but OS X
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should use it just fine.
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Certainly there have ben problems with custom
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monitor profiles under OS X,
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however. Are you sure this tag is the culprit, and
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that it is not some
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specific detail of the data within this tag? I'd try
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copying and pasting the
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VCGT from some profile that works into the one that
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doesn't and see if that
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fixes it, just as a test.
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>
C. David Tobie
>
Design Cooperative
>
email@hidden
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