Patent ID: RE42186

Claim:
A data transform apparatus for converting four items of input data X 0 , X 1 , X 2 and X 3 into four items of data in a frequency space, wherein the input data X 0 , X 1 , X 2 and X 3 are integers, the apparatus comprising: a first multiplier configured to multiply the input data X 1 by a first coefficient; a second multiplier configured to multiply the input data X 2 by a second coefficient; a first rounding processor configured to perform rounding processing on an output of said first multiplier; a second rounding processor configured to perform rounding processing on an output of said second multiplier; a first calculator configured to add an output of said first rounding processor to the input data X 0 ; a second calculator configured to add an output of said second rounding processor to the input data X 3 ; a third rounding processor configured to obtain difference data between an output of said first calculator and an output of said second calculator, to multiply the difference data by a third coefficient and to perform rounding processing on the result of multiplication of the difference data by the third coefficient; a third calculator configured to add an output of said third rounding processor to the input data X 1 ; a fourth calculator configured to add an output of said third rounding processor to the input data X 2 ; a fourth multiplier configured to multiply an output of said third calculator by the second coefficient; a fifth multiplier configured to multiply an output of said fourth calculator by the first coefficient; a fourth rounding processor configured to perform rounding processing on an output of said fourth multiplier; a fifth rounding processor configured to perform rounding processing on an output of said fifth multiplier; a fifth calculator configured to add an output of said fourth rounding processor to an output of said second calculator; and a sixth calculator configured to add an output of said fifth rounding processor to an output of said first calculator, wherein the outputs of said third, fourth, fifth and sixth calculators are output as the four items of data in the frequency space.