| abstract |
(57) [Problem] To reduce the bit rate of a bit stream compression-encoded by the MPEG-2 system while minimizing image quality deterioration of a decoded image. An inverse quantization device inversely quantizes an MPEG-2 bit stream and outputs discrete cosine coefficients in DCT block units. The band limiting device 27 replaces the value of the horizontal high-frequency component of the discrete cosine coefficient with 0. The quantization device quantizes the discrete cosine coefficient with a quantization width different from the original quantization width. |