IMAGE ENCODING DEVICE, IMAGE ENCODING METHOD, AND COMPUTER PROGRAM

PROBLEM TO BE SOLVED: To prevent image degradation associated with repetition of encoding and decoding processes of an input image. SOLUTION: Rounding of a value of a DC component of a DCT coefficient after being subjected to Hadamard transform is performed by round to the nearest even (JIS rounding method) instead of conventional 8/16 rounding (round half up). As for rounding errors, since round up and round down are determined depending on whether a rounding result is even or odd, a phenomenon where rounding errors accumulate at the same part can be avoided. Alternatively, 15 is used for a value of an element equivalent to a DC component of a quantization matrix instead of 16, and thereby rounding of a maximum error is prevented from occurring even when 8/16 rounding is performed. COPYRIGHT: (C)2011,JPO&INPIT