Flate compression (which is implemented by zlib),
The algorithm is at http://www.zlib.org/zlib_docs.html and you have
the zlib source code in C and ports to other languages.

    reference from adobe says very little about that filter, it just states
    it's similar to lzw.


Look at the bibliography, the part about RFC1950 and RFC1951.
I'm not sure what you expect to find other than this.

http://www.ietf.org/rfc/rfc1951.txt !!