RE: Content negotiation: GIF v. PNG

You know about the licensing issues with .gif files, right?

The consensus seems to be that if you're using GIFs you should think about
moving them over to PNG, however at the moment, as Terje wrote, not all
clients can support PNG - the choice of when to change is up to you. I think
W3C are doing their best to support as many people as possible and have used
this as a half-way house. 


-----Original Message-----
From: Peter Foti (PeterF) []
Sent: 05 March 2001 20:34
To: ''
Subject: RE: Content negotiation: GIF v. PNG

I question why this is done at all?  Why is PNG the preferred format?
It seems that if the validator was just changed to always offer the GIF
file, then no one would have this problem, and the world would be a
better place! :)  There would be no additional server configuration
required, plus you wouldn't have to worry about supporting both a PNG
version and a GIF version of the file.  It would seem logical to rely on
the method that is most portable and requires the least amount of


-----Original Message-----
[]On Behalf Of Brian Gilkison
Sent: Monday, March 05, 2001 3:14 PM
Subject: Content negotiation: GIF v. PNG

Some time ago (late '99), Terje gave the following explanation as to why
there was no ".gif" or ".png" extension on the validator <img> tags,
i.e., those generated for validated pages, ala:

    <a href=""><img border="0"
        alt="Valid HTML 4.01!" height="31" width="88"></a>

Terje wrote:
> The filename extension is left out to let the server negotiate with
> client whether to return a GIF file or a PNG file. PNG is the
> format but not all clients can handle it so there has to be a fallback
> to the GIF files. This will of course fail if the server running the
> validator does not have content negotiation enabled.

Although more an Apache question, exactly what directives are required
this to happen?  The above code works unchanged on my ISP's server,
presuming I have an .htaccess file with an "Options MultiViews" entry,
on my personal server it doesn't...  What other directives besides
"Options Multiviews' might be required?


>  Brian Gilkison           | <
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Received on Tuesday, 6 March 2001 06:03:54 UTC