IBM Quick Reference Guide - 1992

[der Mouse]

>> GIF is pretty good, [...]
> I recommend that you use PNG instead of GIF -- better compression and
> better features.

Certainly lots more features, which in actually a reason to avoid it,
at least to me.  PNG 1.1's spec is three times the size of GIF 89's
(comparing a text file I have lying around for GIF89 versus RFC2083 for
PNG); just glancing over the table of contents for RFC2083, it looks
like second-system effect applied to TIFF.

It is approximately impossible to implement PNG compactly; you need
something functionally equivalent to zlib (see the first bullet point
in RFC2083 section 12.3); pngtopnm is some three to four times the size
of giftopnm.  (I find pngtopnm is 128981 bytes versus giftopnm at 31373
bytes, a factor of 4.11+; after stripping symbol tables, 96016 versus
25480 bytes, a factor of 3.626- - and while shared libraries make this
comparison unfair, they do so in png's favour, for the pngtopnm I
looked at is linked shared against libm and libc, while the giftopnm,
only libc.)

> Besides, I thought the GIF patent had expired everywhere?

Nitpick: I don't think GIF is patented anywhere.  Rather, it uses
Lempel-Ziv-Welch compression, and *that* is patented - or at least was;
I don't know enough about patent expiration times in various
jurisdictions to know where its patents have died.

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