Operation device and operation method for discrete cosine transform and inverse discrete cosine transform

摘要

With addition/subtraction and product-sum operation procedures, a one- dimensional N-order discrete cosine transform (DCT) operation is performed so that N pieces of DCT results can be obtained from N pieces of original image data with arguments from 0 to (N-1). In the addition/subtraction procedure, among M pieces of data with arguments from 0 to (M-1) (M is a positive integer expressed as a positive power of 2 from 2 to N), two data for which the sum of the arguments is M-1 are subjected to addition/subtraction for (log.sub.2 N - 1) times to obtain M/2 pieces of addition results and subtraction results with arguments from 1 to (M/2-1). In the product-sum operation procedure, L pieces of data with arguments from 0 to (L-1) (L is a positive integer expressed as a positive power of 2 from 2 to N/2) and L.sup.2 pieces of DCT coefficients are subjected to product-sum operation for (log.sub.2 N - 1) times to obtain and output L pieces of DCT results. Two data with arguments from 0 to 1 and four DCT coefficients are subjected to product- sum operation once to obtain and output two DCT results.