Reconstruction of degraded image sequences. Application to film restoration

摘要

A suitable detection--reconstruction approach is proposed for removing impulsive distortion and other types of deterioration from degraded image sequences. The main application that has motivated this work is the problem of digital film restoration for the movie industry, which has only very recently been explored. Line artifacts, which are prominent degradations in motion picture films, are also considered here. The detection procedure consists of two steps. First, a morphological filter provides impulsive distortions and line scratch candidates. Unlike impulsive distortions, which appear randomly in an image, line artifacts persist in nearby or the same location across several frames. Furthermore, the detection process is complicated by the fact that lines occur as natural part in interesting scenes. Therefore, we add a validation step for separating possible line defects from false detections. It consists in tracking the potential line artifacts over the frames using a Kalman filter. An interpolation technique, dealing with both low and high frequencies around the detected deteriorations, is investigated to achieve a nearly invisible reconstruction of damaged areas.