A forward-mapping realization of the inverse discrete cosine transform

The paper presents a new realization of the inverse discrete cosine transform (IDCT). It exploits both the decorrelation properties of the discrete cosine transform (DCT) and the quantization process that is frequently applied to the DCT's resultant coefficients. This formulation has several advantages over previous approaches, including the elimination of multiplies from the central loop of the algorithm and its adaptability to incremental evaluation. The technique provides a significant reduction in computational requirements of the IDCT, enabling a software-based implementation to perform at rates which were previously achievable only through dedicated hardware.<>