| 摘要 |
PURPOSE:To reduce the dimensions of a conversion table at the time of compressing data and inversion table at the time of restoring the data by providing a switching device to switch the inputs and outputs of the conversion table and a simple code converter and causing the existence of a prescribed length code and the changeover of an input/output path to correspond. CONSTITUTION:At the time of compressing the data, not that all codes are code-converted by a conversion table 11, but that the data in a necessary range are code-converted by using the conversion table 11, and the data outside the necessary range are code-converted with a simple method to add a prefix to the former code by the simple code converter, etc. Namely, for example, only the data, in which an appearing frequency is comparatively large, are code- converted by using the conversion table 11, and as to the data such as a JIS level-2 KANJI (Chinese character) in which the appearing frequency is comparatively small, the conversion is executed in adding a code for deciding with a prescribed length such as the prefix. Consequently, a code conversion table corresponding to the JIS level-2 KANJI, etc., does not need to be prepared. Thus, the dimensions of the conversion table at the time of compressing the data and inversion table at the time of restoring the data can be reduced. |
