| 摘要 |
PURPOSE:To prevent the thickening of the dictionary where character strings are registered and to efficiently perform the compression processing of image data, when an encoding is performed by an LZW method. CONSTITUTION:Before an encoding is performed in an encoding means 1-3, image data is converted with a conversion means 1-1 in the following way. The conversion means 1-1 performs the processing of original image data every line and outputs the data by substituting the code showing that the line is the same character line for it when the line is composed of all the same characters. When the line with the same array exists before the line, the line is outputted after substituting the code showing that the same line exists. In the case of the line which does not conform to either one of them, the line data is outputted by attaching the code showing a noncoincidence. When a decoding to original image data is performed, a reverse conversion to original image data is performed for data by a reverse conversion means 1-2 after the data is decoded to conversion data by a decoding means 1-4. |
