Message-Id: <200201291736.g0THaRg20986@sitelicense.arizona.edu> Date: Tue, 29 Jan 2002 10:35:36 -0700 From: Tim Au Yeung <mailto:ytau@UCALGARY.CA> Subject: Re: Zipping image files To: mailto:IMAGELIB@LISTSERV.ARIZONA.EDU
<pre>
Based on the specification of TIFF -- no. The header data is stored (within
the file that is) separately from the image data. Profiles are embedded into
the header information and so aren't affected (to the best of my knowledge).
Zipping isn't going change the file at all as it compresses the file as a
whole (to which is another gain -- ICC profiles can be fairly large and
compressing that using Zip might net you another 500 KB or so).
Tim
----- Original Message -----
From: "Anthony Troncale" <mailto:troncale@AMNH.ORG>
To: <mailto:IMAGELIB@LISTSERV.ARIZONA.EDU>
Sent: Tuesday, January 29, 2002 10:12 AM
Subject: Re: Zipping image files
>
> Question: Does Zipping or any other compression of a TIFF file change the
> color profile of a color image? Header information?
>
> Anthony Troncale
> American Museum of Natural History
>
>
> At 09:58 AM 1/29/02 -0700, you wrote:
> >As a couple of other people pointed out, both TIFF and the ZIP format use
a
> >non-lossy compression format -- your gains will be minimal at best if
you're
> >using a compressed TIFF. I can, however, see one argument of when using
ZIP
> >on TIFF files might make sense:
> >
> >If all of your files are uncompressed TIFF (regardless of type; bitonal,
> >greyscale, colour, etc.), then for archiving purposes, you only need to
> >emulate two applications: one for decoding an uncompressed TIFF and one
for
> >unzipping instead of having an application that has to handle multple
> >compression algorithms. This could simplify archiving -- I believe
there's
> >an open-source version of ZIP (gzip) and the general TIFF format is a
> >published spec. so both could be implemented in new platforms in the
future
> >relatively easily. Using proprietary algorithms (as could be bundled into
> >TIFF -- the spec. really doesn't care what compression algorithm you use)
> >might have implications from an archiving perspective.
> >
> >Tim
> >---------
> >Tim Au Yeung
> >Manager, Digitization Initiatives
> >Information Resources
> >University of Calgary
> >
> >
> >----- Original Message -----
> >From: "David Adams" <mailto:David.Adams@NATLIB.GOVT.NZ>
> >To: <mailto:IMAGELIB@LISTSERV.ARIZONA.EDU>
> >Sent: Monday, January 28, 2002 12:41 PM
> >Subject: Zipping image files
> >
> >
> > >
> > > Does anyone know if there is any form of change to digital image files
by
> >using WinZIP or 'zipping' applications?
> > >
> > > I am interested to know if this will have an affect on TIFF files that
are
> >to be used for long term preservation.
>
</pre>
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