| 摘要 |
<p>The invention relates to a method for encoding video signals corresponding to a sequence of frames constituted either from video-type images or film-type images. These film-type images are obtained by means of the 3 : 2 pull-down technique involving a subdivision of each film frame into two fields and a duplication of two fields within each group of four subdivided frames. According to the invention, the encoding step of the signals is preceded by a preprocessing step that comprises the sub-steps of : (A) thresholding the eight absolute values of the successive pixel-to-pixel differences between fields of the same parity ; (B) measuring the density of '1' (resp.'0') per block of m x n pixels of the field structure, said measure leading to mark each pixel as 1 or 0 ; (C) detecting in any group of ten successive fields within the preprocessed signals thus obtained, the film pattern formed by said duplicated fields ; (D) switching said preprocessed signals from a first encoding mode to a second one, when said film pattern is detected, or from the second one to the first one, when it is not detected ; (E) encoding said switched signals according to the first mode or to the second mode.</p> |
