Methods and apparatus for preventing rounding errors when transform coefficients representing a motion picture signal are inversely transformed

摘要: Mismatch error occur in the local decoder of a MPEG-standard compressor for motion picture signal, and an expander compressed signal. This is because lack standard rounding results *.5 (* integer) obtained when set transform coefficients resulting from compressing signal inversely orthogonally transformed. The invention prevents mismatch errors by preprocessing prior to inverse othogonal (15). are summed (23A) parity (odd or even) sum judged (21). When be even, one inverted (28) provide parity-inverted coefficient. makes odd. Then, indluding coefficient transformed (15), none orthogonal will have value *.5.