Patent ID: 7912318

Claim:
A data transform apparatus, which transforms four integer-represented input data into one DC coefficient and three AC coefficients on a frequency space, which are represented by integers, and outputs the DC coefficient and AC coefficients, the apparatus comprising: a DC coefficient generating unit which summates the four input data, halves the summation result and converts the halved result into an integer by applying one of two round processes including processing for rounding up a fractional part and processing for truncating a fractional part, and outputs the calculation result as the DC coefficient; an intermediate data generating unit which generates, as intermediate data, a difference value between one input data of the four input data, and the DC coefficient obtained by said DC coefficient generating unit; and an AC coefficient generating unit which generates three AC coefficients of integer by adding or subtracting the intermediate data generated by said intermediate data generating unit to or from three input data except for the one input data, wherein the DC coefficient generated by said DC coefficient generating unit and the three AC coefficients generated by said AC coefficient generating unit are output as lossless-Hadamard transform coefficients.