| 摘要 |
<p>PROBLEM TO BE SOLVED: To decrease the frequency of addition for rounding to one and to speed up M-point×N-point two-dimensional IDCT operation by adding a specific number to the DC coefficient of an input. SOLUTION: A DC coefficeint x(0, 0) of an input DCT coefficient is inputted and 2<n-2> is added. An M×N two-dimensional IDCT computing element 2 inputs the output of an adder 1 and DCT coefficients x(0, 1)×(M-1, N-1) and performs M-point×N-point two-dimensional inverse discrete cosine transformation. The computing element 2 performs calculation up to the (k)th bit of a decimal part. A shift computing element 3 shifts the operation result of the M×N two-dimensional IDCT computing element 2 calculated with the (k) bits of the decimal part by (k) bits to the right and outputs it. Consequently, a circuit which performs the M×N two-dimensional IDCT wherein M×N is the (2n)th power of 2 can have the same effect as single-time addition for rounding all arithmetic results and the two-dimensional IDCT operation can be performed fast.</p> |
