Patent ID: 7117236

Claim:
A method for partially carrying out a discrete cosine transform (DCT) on a set of input data values v i based on a coefficient matrix essentially as follows [ u ] = [ C e 0 0 C o ] * [ vp vn ] , where u is a set of output data values, C e and C o are coefficient sub-matrices, vp is a vector of sums of input data values, and vn is a vector of differences of input data values, including: generating from the input data values the vectors vp and vn are generally of the forms [ vp ] = [ vp0 vp1 vp2 vp3 ] = [ v0 + v7 v1 + v6 v2 + v5 v3 + v4 ] and [ vn ] = [ vn0 vn1 vn2 vn3 ] = [ v0 - v7 v1 - v6 v2 - v5 v3 - v4 ] ; iteratively submitting permutations of the vectors vp and vn to first and second adder networks that implement multiplication of the vectors by coefficients common to rows of the sub-matrices C e and C o , respectively; and assembling the set of output data values u from results of the iterative submission of the permutations of the vectors to the adder networks.