METHOD FOR IMPLEMENTING APPROXIMATION OF DISCRETE COSINE TRANSFORMATION, QUANTIZATION, INVERSE QUANTIZATION AND APPROXIMATION OF INVERSE DISCRETE COSINE TRANSFORMATION

摘要

PPROBLEM TO BE SOLVED: To decrease operations necessary for a normal discrete cosine transformation (DCT) and an inverse discrete cosine transformation (IDCT) and assure high quality of decompressed digital data. PSOLUTION: This invention relates to an approximation of a DCT and quantization which are to be applied continuously to digital data for compression of the digital data. In order to improve the transform, a predetermined transform matrix is simplified to require less operations. In addition, elements of the simplified transform matrix constituting irrational numbers are approximated by rational numbers. These measures are compensated by extending predetermined quantization to compensate the approximation by the rational numbers of the elements of the simplified transform matrix. If the simplified transform matrix and the extended quantization are used as a basis for implementation, a fast transform with a good resulting quality can be achieved. An approximation of an IDCT employed in decompression of compressed digital data can be simplified correspondingly. PCOPYRIGHT: (C)2007,JPO&INPIT