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From: Frank on 10 Feb 2010 06:02
V10.6.2
When I highlight a 2.7 mb file on desktop and click on compress on
finder file pulldown menu the result is a 2.6 mb zip. That is hardly
worth the effort when I need a file less than 1 mb in size. Is this
the best it can do, or am I missing some technique?
From: Malcolm on 10 Feb 2010 06:13
On 2010-02-10 06:02:02 -0500, Frank said:

> V10.6.2
> When I highlight a 2.7 mb file on desktop and click on compress on
> finder file pulldown menu the result is a 2.6 mb zip. That is hardly
> worth the effort when I need a file less than 1 mb in size. Is this
> the best it can do, or am I missing some technique?

It depends on the file Most picture, audio, and video formats are
already compressed, so won't get much smaller. Text files compress
well.

From: Frank on 10 Feb 2010 06:56
On Feb 10, 6:13 am, Malcolm <malcolm(a)invalid> wrote:

>
> It depends on the file  Most picture, audio, and video formats are
> already compressed, so won't get much smaller.  Text files compress
> well.

What about pdf files?


From: Jamie Kahn Genet on 10 Feb 2010 06:58
Frank <gno52(a)windstream.net> wrote:

> V10.6.2
> When I highlight a 2.7 mb file on desktop and click on compress on
> finder file pulldown menu the result is a 2.6 mb zip. That is hardly
> worth the effort when I need a file less than 1 mb in size. Is this
> the best it can do, or am I missing some technique?

Well it's not magic :-) If the items are JPEG files, H.264 video or MP3
music files (to give just a few of many examples) then they're already
highly compressed formats, leaving little benefit to further applying
lossless compression (which is what the ZIP format uses) to them. If on
the other hand the items are text files, say, then it's likely ZIPing
them will result in much smaller files.

In other words it all depends on the format of the files you're trying
to zip. If the format already includes substantial compression there
won't be much more lossless (compression that throws no information
away) compression can do. This is common for most video, photo and audio
formats you'll encounter, unless you work with digital photo, video or
music editing where uncompressed high quality versions are typically
used before outputting a final smaller lossy (throws information away to
achieve a smaller file size) compressed product.

So what is it you're trying to compress?

Regards,
Jamie Kahn Genet
--
If you're not part of the solution, you're part of the precipitate.
From: David Empson on 10 Feb 2010 08:12
Frank <gno52(a)windstream.net> wrote:

> On Feb 10, 6:13 am, Malcolm <malcolm(a)invalid> wrote:
>
> > On 2010-02-10 06:02:02 -0500, Frank said:
> >
> > > V10.6.2
> > > When I highlight a 2.7 mb file on desktop and click on compress
> > > on finder file pulldown menu the result is a 2.6 mb zip. That
> > > is hardly worth the effort when I need a file less than 1 mb in
> > > size. Is this the best it can do, or am I missing some
> > > technique?
> >
> > It depends on the file Most picture, audio, and video formats are
> > already compressed, so won't get much smaller. Text files compress
> > well.
>
> What about pdf files?

A PDF containing images is likely to have a fair degree of compression
already. The only way you can significantly reduce its size is to reduce
the quality of the images in the PDF.

One way to do this is with Preview. If you open a PDF in Preview and do
a "Save As", you can choose a Quartz Filter, which will modify the PDF
in various ways. One of the options is "Reduce Quality", but you have no
control over the degree of reduction.

There are presumably tools which can do this with better control.

--
David Empson
dempson(a)actrix.gen.nz
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