| 摘要 |
<P>PROBLEM TO BE SOLVED: To avoid deteriorating the image quality of a decoded image due to a marked increase of the block distortion. <P>SOLUTION: An orthogonal transformer 11 divides digital image signals into blocks, and executes a discrete cosine transformation to generate coefficient data DA using pixel data in the block. A quantizer 12 quantizes the coefficient data DA to obtain quantized data DB and, if the number of AC component coefficients contained in the data DB is less than a specified value, again quantizes with a reduced quantization width. A code allotter 13 executes a code allotment based on the quantized data DB to generate coded data DC. A buffer 14 stores the coded data DC and an output unit 15 outputs the stored coded data DC as an output signal DTout at a specified bit rate. The quantization width is varied according to a control signal DB, based on the quantity of data stored in the buffer 14. <P>COPYRIGHT: (C)2004,JPO |
