Verfahren zur Durchführung der inversen, diskreten Kosinustransformation

摘要

A method of performing an inverse discrete cosine transform (IDCT) capable of reducing the amount of calculation while satisfying bit accuracy required by international standards. The IDCT method comprises the steps of defining each column of scalars Xij (where, i,j=0,1,2, . . . , N-1) and Yij as a vector +E,dot X+EE i={Xi0, Xi1, . . . , Xi(N-1)} and a vector +E,dot Y+EE i={Yi0, Yi1, . . . , Yi(N-1)}, respectively, storing values of in a scalar register, storing values of +E,dot X+EE i={Xi0, Xi1, . . . , Xi(N-1)} in a vector register, obtaining +E,dot Y+EE i={Yi0, Yi1, . . . , Yi(N-1)} by reading out the values stored in the scalar register and the vector register and by parallel-processing scalar-vector multiplications and vector-vector additions with respect to the readout scalar values and vector values according to the equation obtaining values of a one-dimensional IDCT in a first direction by performing the one-dimensional IDCT in the first direction by repeatedly performing the above described steps N times, obtaining a transposed matrix of the obtained one-dimensional IDCT values in the first direction, and obtaining values of a final two-dimensional IDCT by obtaining values of the transposed matrix in the same manner as the one-dimensional IDCT in the first direction and obtaining a transposed matrix of the obtained values to perform a one-dimensional IDCT in a second direction.