DYNAMIC DECIMAL POINT SYSTEM, DYNAMIC DECIMAL POINT ARITHMETIC METHOD, AND APPARATUS AND METHOD FOR 2 DIMENSIONAL INVERSE DISCRETE COSINE TRANSFORM

摘要

PROBLEM TO BE SOLVED: To provide a method of an inverse discrete cosine transform (IDCT) for reproducing a compressed image with high fidelity by limiting an accumulation of round-off errors of the decimal point arithmetic.;SOLUTION: The method of the inverse discrete cosine transform includes a step for receiving a temporary data t'(k, v) with 30 bits as a result of executing a one dimensional inverse discrete cosine transform, a mode 0 step for reserving a memory for 11 bits (without including a sign bit S) for use of an integer when the temporary data is stored in an external RAM if the integer of the data t'(k, v) is not within a range of -128 to +127, and a mode 1 step, which, on the other hand, reserves 7 bits (without including a sign bit S) for the integer if the integer is within the range of -128 to +127 and allocates remaining 4 bits to the decimals. Consequently, the method can increase the accuracy of computing the data t'(k, v) without expanding the external RAM required for temporally storing the data t'(k, v).;COPYRIGHT: (C)2005,JPO&NCIPI