| 摘要 |
PROBLEM TO BE SOLVED: To obtain a fixed length image coder high in compression efficiency by combining block truncation coding with 0 run length of gradation width information. SOLUTION: This image coder is provided with a block truncation coder that encodes data in the unit of blocks consisting adjacent pixels, a 1st coding means that counts consecutive blocks received from the block truncation device and whose gradation width information is 0 and encodes data based on the count, and a 2nd coding means that encodes data based on the gradation width information from the block truncation coder and coded data when the gradation width information received from the block truncation coder is higher than a prescribed value. Input image data are divided into prescribed blocks by a block generating section 10 in the image coder. Then data of each block is encoded byblock truncation coding consisting of a mean value information calculation section 12, a gradation width information calculation section 14 and a coding information calculation section 16. |
