[Clipart] [Bug 3347] PNG files not optimized

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Mon May 23 13:35:02 PDT 2005


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------- Additional Comments From andrew.archibald at mail.mcgill.ca  2005-05-23 13:35 -------
(In reply to comment #9)
> > if one of the programs pngcrush, optipng, or pngout were installed 
> > on the server
> 
> At this time, what's installed on the server is almost totally irrelevant.
> Thumbnails are not generated on the server.  There has been talk of having
> thumbnails generated at upload time, but at this time that is very much 
> LATERed, as there are substantially more important changes that need to be 
> made to the upload facility, e.g., to correctly handle non-ASCII characters
> in the metadata being added.

So, just to be sure: who runs generate_thumbnails.pl? It would be simple to add
a line calling any of optipng, pngcrush, or pngout, provided the user has them
installed. 

> > The best program to use, is OptiPNG. And it's actually better (more
> > user-friendly) to make the files slightly larger, by using Adam7
> 
> I do not understand how the technical details of how the images are 
> internally encoded could possibly make any difference whatsoever in terms
> of user-friendliness.  End users do not know or care about that stuff.
> Making the download filesize smaller is the only difference I can
> possibly imagine improved PNG optimization making to the end user.
> 
> > This is much more user-friendly for low-bandwidth users than making the
> > images even smaller by not using Adam7.
> 
> I especially don't understand how larger filesizes improves anything
> for low-bandwidth users.  Please explain.

This interlacing scheme renders the images progressive - it becomes possible to
render previews as they are downloaded, so that users can see a lower-resolution
version and abort if this is not the image they want.  

Since our PNGs are 128x128, and Adam7 is by no means universally supported (for
 example, I don't think the python-imaging library can read them at all) I don't
think this interlacing is a good idea.           
     
     
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