| 摘要 |
PURPOSE:To provide expandability by which restoration is properly made even if there exists a difference in dictionary memory capacity between a coding side and a decoding side by instructing an usable dictionary memory capacity in a data compression and restoration by a LZW code which is known as an improved version of an incremental resolving type which is a kind of an universal code. CONSTITUTION:Encoded data are divided into partial sequences which differ from each other, and respective partial sequences are attached different reference numbers to be registered in a dictionary 10, and an input data is encoded and compressed by specifying the reference number of the partial sequence whose maximum length coincides with, from in the dictionary 10. At this time, an encoder 100 is provided with a dictionary capacity specifying part 12 which specifies a dictionary capacity usable for encoding, and encoding process is executed by using a dictionary capacity specified by the dictionary capacity specifying part 12, and that capacity is attached to the top of the compressed data as an index. Therefore, restoration can be made when a memory capacity on the decoding side is equal or larger than that on the coding side, and the used capacity can be restrained to a minimum which is required. |
