| 摘要 |
PURPOSE:To achieve the optimum data compression for each group of image data by generating Hoffman code tables for respective groups of image data, and transmitting the code tables together with the groups of compressed data. CONSTITUTION:A change point detector 2 triggers a memory 2 and a total memory and also clears a counter 1 at every change point of an image signal. As a result, white run-length data and black run-length data are written alternately in the memory 3, and a frequency distribution table showing the frequencies of run-length appearance including white and black runs is constituted in the total memory 41. According to this frequency distribution, a code table generating circuit 42 assigns a code which corresponds to the frequency of appearance, and the code is stored in a code table 43. The same image is scanned again and the code table 43 is read out by using the run length of image data stored in the memory 2 as an address to output a Hoffman code which corresponds to the run length to a reception part. |
