| 摘要 |
PROBLEM TO BE SOLVED: To reduce the degradation of image quality when a compression encoding is performed by a specified group when still images are outputted plural numbers of times and transmissions/recordings are performed. SOLUTION: An orthogonal transformation processing part 5 performs an orthogonal transformation of the image data from a memory 3 into the block unit consisting of plural picture elements, and quantizations and encodings are performed in a quantizer 6 and a variable length encoder 8 so that the X (=N×Y) transformed blocks may be code amount of a prescribed range. When the same image is repeated outputted and is made a still image, the X blocks are divided into N groups and quantization characteristics are imparted to every Y blocks from each group. At the time, the quantization characteristic with little degradation of image quality is made to be imparted to a specified group and while the same image is repeatingly outputted, the specified group is made to be changed. At the time of a decoding, only the data with little degradation of image quality is selected and an image is formed based on the information showing the characteristic at the time of the quantization from an inverse quantizer 13 by a memory control circuit 15. |
