Tunes the compression algorithm.
Z_DEFAULT_STRATEGY: For normal data (Default)Z_FILTERED: For data produced by a filter or predictorZ_HUFFMAN_ONLY: Force Huffman encoding only (no string match)Z_RLE: Limit match distances to one (run-length encoding)Z_FIXEDprevents the use of dynamic Huffman codes
Z_RLE is designed to be almost as fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data.
Z_FILTERED forces more Huffman coding and less string matching, it is somewhat intermediate between Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Filtered data consists mostly of small values with a somewhat random distribution.