ENCODING AND DECODING METHOD FOR MOVING IMAGE

摘要

PROBLEM TO BE SOLVED: To prevent the accumulation of errors and to improve the picture quality of reproduced images by applying the composition of images which are performed by the motion compensations using the positive and negative rounding operations. SOLUTION: When the intensity value is interpolated for the composition of preatteted images, the motion compensations performing the positive and negative rounding operations are defined as the motion compensations which uses the positive and negative rounding operations respectively. The expected value of the rounding error of the P- frames is equal to that of the P+ frames in terms of the absolute value and is adverse to each other in terms of codes. Thus, it is possible to prevent the accumulation of rounding errors by making the P+ and P- frames appear alternately to a time base. In order to attain this process, the frames 503 and 507 are defined as P+ frames with the frames 505 and 509 defined as P- frames respectively. As a result, the picture quality of reproduced images can be improved.