A LEMPEL-ZIV DATA COMPRESSION TECHNIQUE UTILIZING A DICTIONARY PRE-FILLED WITH FREQUENT LETTER COMBINATIONS, WORDS AND/OR PHRASES

摘要

The adaptive compression technique improves the Lempel-Ziv (LZ) technique because it reduces the required storage space (18) and transmission time with transferring data (22). Pre- filled compression dictionaries (48) are utilized to resolve prior problems with the Lempel-Ziv technique where compression software starts with an empty compression dictionary and little compression is attained until dictionary has been filled with sequences comm on in the data being compared. The compression dictionary (48) is pre-filled with letter sequences, words and/or phrases that are commonly found in the compressed area. They may be used in the pre-filled dictionary where they are determined by sampling text data from t he same text genre. Initially, multiple pre-filled dictionaries (52) may be utilized by the software, where the most appropriate dictionary for maximum compression is identified and used to compress current data. These modifications are made to any of the known Lempel-Ziv compressio n techniques based on the variants detailed in 1977 and 1978 articles by Ziv and Lempel.< /SDOAB>