Data on PDF vs PS (Was Re: Online docs page should ..) [With prelim patch]

[Geoff Keating]

Marc Lehmann <pcg@opengroup.org> writes:

> On Tue, Dec 21, 1999 at 12:22:12PM +0100, Jan Vroonhof <vroonhof@math.ethz.ch> wrote:
> >  > At least this point is proven with your data (so there is not really a
> >  > lakc of knowledge in this point ;). both gzipped und plain pdf files are
> >  > larger than gzipped ps files.
> > 
> > Yes, but the gzipped pdf files are only about 10% larger. 
> 
> Ok. I still fail to see the added benefit of first compressing with lzw
> (pdf) and then with gzip, and then still having larger files ;)

PDF files generated with free software, or with modern versions of the
Adobe tools, invariably use gzip compression internally too.
The reason they still shrink when you gzip them again is that
the metadata is in plain-text to support incremental downloading and
viewing single pages without having to decompress the whole thing.

> > My browser unzips it just fine before sending it to the PDF viewers.

The disadvantage of compressing the whole file is that then your
browser must download the whole file before showing you the first page.
If you don't compress it, have a newer HTTP server, and have the right
plug-in for your browser, it can download a page at a time and show
you the first page as soon as it gets it.

-- 
- Geoffrey Keating <geoffk@cygnus.com>