Method and apparatus for converting image information

摘要

A technique is disclosed for reducing the bit rate of a bit stream coded into a compressed form according to the MPEG-2 standard, without causing significant degradation in image quality of a decoded image. An inverse DCT converter dequantizes a MPEG-2 bit stream and outputs resultant discrete cosine transform coefficients for each DCT block. A band limiter replaces the values of high-frequency components of the discrete cosine transform coefficients in the horizontal direction, with 0. A quantizer quantizes the discrete cosine transform coefficients using a quantization step value different from the original value.