Re: ColorSync Utility Profiles CMM choice and Profile Flags
Re: ColorSync Utility Profiles CMM choice and Profile Flags
- Subject: Re: ColorSync Utility Profiles CMM choice and Profile Flags
- From: "Bruce J. Lindbloom" <email@hidden>
- Date: Tue, 27 May 2003 11:16:42 -0500
Nick Walker wrote:
>
/library/ColorSync/Profiles - Adobe RGB (1998) Phase One supplied Adobe RGB
>
(1998) profile. Flags = Best Quality
>
>
/library/Application Support/Adobe/Color/Profiles/Recommended/ Adobe RGB
>
(1998) Flags = Normal quality
>
>
Why the different flag qualities is Adobes' Normal' inferior to Phase Ones'
>
Beset Quality or have Phase One just substituted Adobes term from Normal to
>
Best for reasons only known to them?
Bruce Fraser responded:
>
I don't think there's a single current CMM that uses the "quality" flag,
>
which was specific to early implementations of ColorSync that allowed CMMs
>
to choose different degrees of precision to trade speed for quality.
Bruce is right. In addition, note that this "quality" bit in the ICC profile
header is a renegade Apple thing. You will find no mention of it in any
version of the ICC profile specification. In fact, by setting this bit, you
could cause an ICC profile to become illegal, since reserved bits in the
header must be set to zero. Some additional information about the quality
bit may be found here <
http://developer.apple.com/qa/c/cs03.html>. The
staleness is indicated by the May 1995 date! Abhay Sharma's profile
evaluation reports used to place great importance on this bit (maybe they
still do -- I no longer read them), a point of contention I have had with
him in the past.
--
Bruce J. Lindbloom
email@hidden
http://www.brucelindbloom.com
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