An image decoding apparatus for obtaining a decoded image by decoding an encoded data

Abstract From the Canadian patent

A computer-implemented dequantization method utilized in video decoding using a processor and memory is provided. The method determines a two- dimensional transform coefficient matrix K by dequantizing a quantization value matrix L. The method comprising steps of inputting an element L ij of the quantization value matrix; inputting a quantization parameter OP; and determining the transform coefficient matrix K. The element K ij of the transform coefficient matrix is determined by using a mantissa portion matrix element B(QP) ij being a function of QP according to the following equation: K ij = L ij x B(QP mod P) ij x 2 B0+QP/P where B0 and P are constants.