| 摘要 |
An orthogonal transform apparatus wherein in N-th order DCT or DST, the multiplier used for weighting N orthogonal coefficients Yi (i=0, ..., N-1) is one of, a combination of two or more of, or a multiple of one of, the following four sets: . COS (i/2N) . SIN (i/2N) . 1/COS (i/2N) . 1/SIN (i/2N) to thereby considerably reduce the number of multiplications in both orthogonal and inverse orthogonal transform as compared with the conventional. Since the number of multiplications required for calculating one orthogonal coefficient can be reduced, it is possible to reduce operation errors to be caused by multiplications. Further, it is possible to improve the operation precision of an orthogonal coefficient for lower frequency components which have an important role from the standpoint of visual sense. Finally, by applying the orthogonal transform apparatus to two dimensional orthogonal transform and two dimensionally weighting after obtaining two dimensional orthogonal coefficients, it becomes possible to reduce the number of multiplications while performing a desired two dimensional weighting. |
