| 摘要 |
PROBLEM TO BE SOLVED: To provide a coder and a decoder for image data by which coding and decoding processing is applied to synthesized image data efficiently. SOLUTION: A quantization setting section 1 sets a valid range of a quantized DCT coefficient and a quantization control circuit 4 controls a quantization circuit 5 to validate the quantization DCT coefficient in a set valid range. When a block of input image data A, B is given to an orthogonal transformation circuit 6, the quantization circuit 5 assigns the valid range to the data A and assigns an outside of the valid range of the data B. A quantization coefficient synthesis circuit 7 synthesizes the quantization coefficients of the two images into one block. Thus, in the case of decoding the coded data, the coded data of the synthesis block are separated into separate blocks and then decoded sequentially. The synthesis image is detected on a display device as soon as decoding is made. |
