Detection and restoration of color-timing echo artifact for HD digital cinema films

A novel method for automatically detecting and restoring the color timing echo artifact which may result in the internegative/interpositive printing process is proposed. This degradation appears at shoot change, either on the top of the last frame of a shot or on the bottom of the subsequent frame of the next shot. In our work, the degraded region is firstly detected and then restored by using the histogram specification (HS) based method. To avoid discontinuities between the restored region and the remaining of the treated frame due to abrupt modification in a large region, the degraded zone is decomposed into several overlapped small blocks. Then a block matching algorithm is used and a block similarity metric based on ordering has also been proposed for motion estimation under luminance variation. The proposed method is tested on several color high definition (HD) films with highly promising results.