[ILUG] OT: Image formats

[Niall O Broin]

On Wed, Jun 07, 2000 at 04:01:13PM +0000, Mr. B. wrote:

> i should have prefaced the question with information on where they are going to be used.
> they will be used on mainly Win9* platform, in a law firm, for their 
> intranet. So I would guess that file size wouldn't be too much of a problem.
> they would be used within HTML files.
> 
> hmm, so tiff *maybe* the way to go?

Absolutely not - there's no reason to use TIFFs on webpages, just like
there's no reason to put 120 MPH rated tyres on a Morris Minor. Use JPEG for
photographic images, and GIF for everything else. If you want to be more
politically correct, and use an objectively better format, use PNG instead
of GIF, as long as all your target browsers support them, which you can make
the case in an intranet. Even in an intranet, there's no reason to do a
sloppy job and use files bigger than necessary. I've spent a lot of time on
this with professional photographers, and we use a JPEG quality setting of
50% (this is not really an absolute, but about midway on the scale of
whatever application you use will do) and we get file sizes of around 20K
for pictures of app. 600x400 (they're in a 600x600 bounding box) pixels and
around 4K for smaller pictures in a 200x200 bounding box. In fact, you can
even produce small thumbnails in a 100x100 bounding box at around 1K which
are perfectly usable in terms of seeing what's in the picture.

As you look around web sites, you'll see a lot of much less efficient use of
pictures, esp. 50K GIFs used where a 10K (or smaller) JPEG would be visually
identical. Visually identical is the key phrase - there's absolutely no
sense in delivering to the browser anything which doesn't add to the user's
visual experience.

OK - off the high horse now :-) It's just that I've spent a long time on
this, and I know what's possible/desirable, and I really hate waiting when
some crappily designed web site takes 4 times longer to load than it should.


Kindest regards,


Niall  O Broin