Patent ID: 8452114

Claim:
A decoding apparatus for decoding an encoded image signal, the apparatus comprising: a computer that executes a program that causes the apparatus to function as: an entropy decoding unit that performs an entropy decoding on an encoded image signal to generate quantized information; an inverse-quantization unit that performs an inverse quantization on the quantized information generated by the entropy decoding unit to obtain quantization information; a first inverse-orthogonal transforming unit that performs an inverse-orthogonal transformation on the quantization information obtained by the inverse-quantization unit to obtain a decoded image signal; a quantization error estimation unit that calculates a quantization maximum square error using a quantization matrix used in conjunction with the quantization information obtained by the inverse-quantization unit; a second inverse-orthogonal transforming unit that performs an inverse-orthogonal transformation on the quantization maximum square error calculated by the quantization error estimation unit to obtain a quantization maximum error; an image-quality enhancing signal generation unit that generates an image-quality enhancing signal to enhance an image quality of the decoded image using the decoded image signal obtained by the first inverse-orthogonal transforming unit and the quantization maximum error obtained by the second inverse-orthogonal transformation unit; and an image synthesizing unit that synthesizes the image-quality enhancing signal generated by the image-quality enhancing signal generation unit with the decoded image signal obtained by the first inverse-orthogonal transforming unit.