Re: Profile compression
Re: Profile compression
- Subject: Re: Profile compression
- From: Tom Beckenham <email@hidden>
- Date: Thu, 2 Mar 2006 08:46:19 +1100
Hi Chris,
That's a great idea. I was actually thinking of putting a similar
thing to the PDF/X comittee. Even though PDF/X is meant for
"complete" exchange of pre-press information (except for PDF/X-2), it
would be much better to have URLs to output intents in PDF/X than
"named" registries on color.org.
I'll put that forward your suggestion the ICC as suggested. I like
your idea better because you could include the color data space, and
MD5 of the profile in the header.
Cheers
Tom
On 02/03/2006, at 4:24 AM, Chris Murphy wrote:
Tom,
This is a good example of why the ICC needs to update the
specification to allow for a bodyless profile. Basically it would
contain just the header, and a couple of URLs pointing to the
actual profile data which could then be kept up to date. The
implementation of this by the operating system vendors would
involve caching the body of the profile so that it would first
search locally and then if not found there it would use the URLs in
the profile header to locate that data (and then cache it for
future use).
This doesn't solve your problem now, but we really need the ICC to
get on the stick. This has been a big pain point for CMYK based
workflows (among a number of other unrelated things), and I predict
it will be a problem for the larger ICC v4 versions of editing
space profiles such as sRGB and Adobe RGB. The ICC has to figure
this out VERY soon, so that the operating system vendors can
implement this in a reasonable time frame. If they do it now, there
is a good chance this could be implemented in the next major
version of the OS's, but if they diddle around for another year or
more on this issue, then it will just be that much longer.
My suggestion is to go to the ICC web site, www.color.org, and
"Ask Phil" in the upper right hand corner. When can we get header
+URL profiles? What's the time frame? The squeaky wheel gets the
oil so I'd make a point of asking this every few months. Standard
time frames for the ICC are glacial.
I've found binary files to not be very compressible, and that
includes ICC profiles. One way vendors make them smaller is to
build them using a smaller table size, which then compromises their
accuracy. Some vendors assume people won't use them for
softproofing, only for B2A conversions, so they'll put in high
quality 33x33x33 matrix tables for B2A but use much smaller A2B
tables to save size, compromising the soft proof quality.
I haven't tried it, but you might give bzip2 a crack at an ICC
profile and see if they come out any smaller than just zip
compression.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
-------------------------------------------------------------
Co-author "Real World Color Management, 2nd Edition"
Published by PeachPit Press (ISBN 0-321-26722-2)
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