Alleged Literature >> pdc >> wp >> png

One Day my PNG will Come

5 December 1999

GIF is obsolete, and, worse, encumbered with Unisys’s claims of a patent on the LZW algorithm for compressing data. PNG is a technically superior format which is not legally encumbered. PNG also has a freely available reference implementation which should make it easy for any browser to suppert. So naturally PNG replaced GIF everywhere sometime in the late 1990s, yes?

Well, no. Despite Unisys’s best efforts to browbeat everyone in to using PNG I find myself unable to subject my website to the png2gif process just yet. The problem is that Microsoft and Netscape dragged their feet in implementing PNG, with the result that I can’t ditch GIF until I can persuade everyone to upgrade to either Netscape Navigator 4.04 or Microsoft Internet Explorer 4 (PC) or 5 (Mac). What’s more, neither of these browsers support transparent PNGs, and I do exploit transparency in my site.

Hm... Now that I think about it, I have to admit that I use transparent images less than I did: the old layout used small quarter-circle images to make curved corners for the blocks of colour. The new tabbed-notebook images have transparent corners (to make them round) but these appear against a fixed background, so could just as easily simply be coloured to match.

Anyway, what I have done so far is upgrade the software on my Linux box to be able to generate PNG files. (This was tougher than it should have been, since many PNG-savvy programs had broken implementations. This is a annoying: why not just get it right the first time? Think about how much the use of cascading style sheets (CSS) has been blighted by the proliferation of badly broken CSS-savvy browsers.) I have decided to use PNG for future projects involving automatically processed images. This is forced on me by Unisys’s revoking their promise to allow GIF licences without charge to software available gratis: the graphics software I use on Linux is all free software (except for XV, which is shareware). As a result, I expect to be adding PNGs to my site in future (not before 2000).

Another change I feel forced upon my by Unisys is the replacement of GIF by JPEG for some of the thumbnail files I have in my newer albums. This is not so bad from a net bandwidth point of view (the files are both small), but JPEG requires more client-side computation to uncompress than GIF does, which will make it take longer to display the pages on computers without much spare CPU power.

All in all, while I feel sad that I can’t justify converting entirely over to PNGs today, I can at least try to avoid adding any new GIFs.


Burn All GIFs Day
A campaign encouraging us to purge our web sites of GIFs.
Unisys not suing (most) Webmasters for using GIFs
Discussion on Slashdot based on an email conversation with Unisys after their change in policy.
No GIFs due to patent problems
Discussion of the GIF problem from the point of view of the Free Software Foundation, on the GNU website.
League for Programming Freedom
The League for Programming Freedom is an organization that opposes software patents and user interface copyrights.

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