Binary Safe Encoding/Compressing of Data

Does anyone know of a way to encode/compress a binary image/data into a PHP file. Is there a function or script that anyone knows about to assist me ? Upon running the PHP file, it will decompress/decode the binary data and then write the uncompressed/unencoded data to a file. I did notice the function 'gzcompress/gzuncompress' but that was good only for PHP4.01 and I would like to have something that would work on PHP3 also. If nothing is currently out there, does anyone have any good starting points for me on creating a function to do this ? Paul