PURPOSE: To enhance a data compression ratio by retrieving plural dictionaries, selecting the dictionary which expresses a longest character string, executing designition through the use of the reference number of the dictionary and executing encoding.
CONSTITUTION: The plural prepared dictionaries are retrieved, the dictionary which expresses the longest character string is selected, designition is executed by the reference number of the selected dictionary and encoding is executed. The longest character string which expresses the repetition of an input character as against the input character is referred to the dictionary, the dictionary which expresses the longest character string is selected and the encoding is executed (S4) by the reference number. In the case of decoding, the plural dictionaries are retrieved, the dictionary which decodes the longest character string is selected and decoding is executed by the reference number of the selected dictionary.
OKADA YOSHIYUKI
YOSHIDA SHIGERU
NAKANO YASUHIKO
