Optimization of Frequency Table Storage in Constant Grade Compression

摘要

In order to improve the efficiency of constant grade compression, it is necessary to save the space occupied by frequency table. Theory of constant grade compression is expatiated in this paper. Since this compression method is related to the frequency of the subsection to be compressed, we make a research on the distribution of the byte frequency. Due to the random subsection content, it is found that frequency times are more in the areas which near the average frequency value and the times are less in the areas which is far from the average frequency value. According to the distribution features of the character, the storage of frequency table is optimized. The different prefix codes are adopted to express the frequencies in different areas so as to save more storage space.