| 摘要 |
PROBLEM TO BE SOLVED: To enhance compression ratio by dividing image data into plural blocks, scanning each block in a vertical direction and a horizontal direction, executing run length encoding, and adopting the code smaller in the amount of codes. SOLUTION: The run length of the data after compression, is defined as 5-bit fixed length whose leading bit is white or black identifier and four bits are fixed. In the case of encoding one block consisting of the 4×4 pixel of an image, left/upper one block is scanned in a horizontal direction to execute horizontal direction encoding processing to count each run length. Next, scanning in a vertical direction is executed and vertical direction encoding processing is executed to count a white or black run length. The numbers of horizontal and vertical run lengths become 8 and 5 and data quantities become 40 bit and 25 bit. Consequently, vertical scanning of a small data quantity is used to encode one block. Continually, the block is moved to be similarly moved and these operation is executed extending the whole blocks. At the time of decoding, processing opposite to this is executed to restore to an original image.
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