Dynamic word based text compression
K.S. Ng, L.M. Cheng, C.H. Wong · 2002
We propose a dynamic text compression technique with a back searching algorithm and a new storage protocol. Codes being encoded are divided into three types namely copy, literal and hybrid codes. Multiple dictionaries are adopted and each of them has a linked sub-dictionary. Each dictionary has a portion of pre-defined words i.e. the most frequent words and the rest of the entries will depend on the message. A hashing function developed by Pearson (1990) is adopted. It serves two purposes. Firstly, it is used to initialize the dictionary. Secondly, it is used as a quick search to a particular word. By using this scheme, the spaces between words do not need to be considered. At the decoding side, a space character will be appended after each word is decoded. Therefore, the redundancy of space can also be compressed. The result shows that the original message will not be expanded even if we have poor dictionary design.