This site contains a collection of comments, impressions, comparisons,
experiments and ideas regarding the
PNG (Portable Network Graphics)
file format, and the related technologies:
ZLIB (Data Compression Format and Library),
and
MNG (Multiple-Image Network
Graphics). It is focused on the compression algorithms used in PNG.
PNG uses ZLIB streams [
RFC1950]
as compressed datastreams. The compression algorithm, called
Deflate
[
RFC1951], was designed by
Phil Katz and used initially in
PKZIP.
Jean-loup Gailly and Mark Adler rewrote the code, avoiding any patented
algorithms. This code, freely available in source, can be found
here.
Additional technical details are provided
here.
A good explanation of the
Deflate algorithm by Antaeus Feldspar
is available
here.
We use the term
ZLIB (written with capital letters) when we refer to the
standard or to standard-compliant streams, and the term
zlib (written
with small letters) when we refer to the reference implementation.
