Image decoding device and image decoding method

An image decoding device, which decodes in target macro block units, coded image signals that are coded by DCT, quantization, and variable-length coding, comprising:

• a target macro block setting means for setting a target macro block to be decoded currently from among an entire image to identify a target macro block;
• a target macro block extraction means for performing a variable length decoding process and a zigzag scan on said coded image signal and extracts data of said target macro block to produce an extracted target macro block data,
• a prediction means for performing a DC/AC prediction process on said extracted target macro block data,
• an inverse quantization means for performing inverse quantization on said target macro block data that have been subject to said prediction process, and
• an inverse DCT means for performing inverse DCT on said target macro block data that have been subject to inverse quantization and outputs an image of said target macro block;
• said prediction means includes a reference value storage means;
• said reference value storage means including means for holding reference values that are necessary for said prediction process performed on said target macro block;
• a prediction computation means for performing prediction computation based on reference values of said reference value storage means;
• a predicted value storage means for holding results of said prediction computation;
• a prediction control means for controlling said reference value storage means, said prediction computation means, and said predicted value storage means;
• and
• a total storage volume of said reference value storage means and said predicted value storage means is smaller than a storage volume of predicted values for an entire image size, and said prediction control means includes means for copying data, necessary for said prediction computation of a next target macro block, from said predicted value storage means to said reference value storage means.