| 摘要 |
PURPOSE:To improve the compressibility of the image data by performing the approximate retrieval of the registered character strings to a dictionary including the patterns and run lengths similar and approximate to each other, coding these retrieved character strings, and registering approximately the character strings obtained by adding the input characters to those registered character strings. CONSTITUTION:The character string inputted from a pre-processing means 10 is retrieved out of a dictionary 12 by a dictionary retrieving meens 14. If the dictionary 12 does not include the character string that is coincident with the relevant character string including the input characters, the characters approximate to the input characters are read out by an approximate dictionary retrieving means 16. Then the means 16 retrieves a character string that is coincident in the largest length with the character string including the approximate characters. A coding means 18 codes the character string retrieved by the means 14 or 16 in a reference number of the dictionary 12. Then the character string obtained by adding the input characters to the reference number of the character string that is coded immediately before detection of a fact that the character string coincident with the character string including the input characters cannot be retrieved out of the dictionary 12 and no approximate character is obtained is registered into the dictionary 12 as a new reference number. |
