Re: untagged RGB data
Re: untagged RGB data
- Subject: Re: untagged RGB data
- From: email@hidden
- Date: Sat, 20 Dec 2003 22:13:46 EST
Chris,
So you're gonna make me look up the spec? OK. Look at section I.3. Basically
it says to use an enumerated colorspace but that you may also (not must)
alternatively embed a restricted ICC profile. That being said, its not inconsistent
with your description of how Adobe requires profile embedding when saving JP2
files. In fact, its smarter, assuming it will be decoded properly later...
Eric Walowit
Tahoe
In a message dated 12/20/2003 10:26:21 AM Pacific Standard Time,
email@hidden writes:
On Dec 20, 2003, at 8:25 AM, email@hidden wrote:
>
Its been a while since I looked at the spec, but as memory serves,
>
JPEG2000
>
and the various extensions have additional colorspace specifiers and
>
alow the
>
embedding of restricted (matrix-TRC) profiles, but I don't think its an
>
absolute requirement.
I can't tell for sure. There is extended JPEG 2000 (jpf) and standard
JPEG 2000 (jp2). An Adobe PDF on CameraRaw and JPEG 2000 says:
"If you want to save a JP2-compatible file, you must select the ICC
Profile option (Windows) or the Embed Color Profile option (Mac OS) in
the Save As dialog box. Otherwise, the JP2 Compatible option will be
unavailable in the JPEG 2000 dialog box."
It also says that JP2 viewers aren't required to support ICC profiles.
Seems like a pretty bad idea to me. (Preview in in Panther ignores
embedded profiles in JP2 files, incidentally.)
In Photoshop CS, after installing the JPEG 2000 plug-in and selecting
it as a format, the Save As dialog box grays out the Embed Color
Profile checkbox and forces it on. There is no way in Photoshop to not
embed a profile in JPEG 2000 format. If you select JP2 compatibility,
there is an additional "Restricted ICC Profile" that gets added. If I
uncheck it, then the "JP2 Compatible" checkbox is automatically
unchecked.
I'm thoroughly confused, in any event. But it does seem that JPEG 2000,
at least as provided by Photoshop, is embedding a profile and there's
no other option. And even though Preview, on 10.3 does not respect
embedded profiles in JP2 files, when you save them it always embeds the
sRGB profile.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
---------------------------------------------------------
Co-author "Real World Color Management"
Published by PeachPit Press (ISBN 0-201-77340-6)
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