Patent ID: 7284026

Claim:
A Hadamard transformation method for processing image data, comprising: executing computer program steps according to a program stored on a computer-readable medium, said steps including a first transformation step of transforming image input signals using a four-point Hadamard transformation matrix in each of four four-point Hadamard transformation units; a first rounding step of rounding up the least significant bit of each of the odd number of four coefficients transformed by each of said four four-point Hadamard transformation units and discarding the least significant bit of each of the remaining odd number of the four coefficients, so as to produce the integer type of four sets of coefficients, each set including four coefficients; a second transformation step of selecting one coefficient from each one set of the four sets such that odd numbers of coefficients among the four selected coefficients for one set were rounded up in said first rounding step, and supplying the four selected coefficients to a four-point Hadamard transformation unit and transforming the four selected coefficients using a four-point Hadamard transformation matrix; and a second rounding step of rounding up the coefficients transformed in said second transformation step so as to cancel propagation errors to be superposed over the transformed coefficients.