Automatic Restoration Algorithms for 35mm film

Classical film restoration is based on special copying machines to improve the quality of safekeeping copies. Only a small class of defects can be removed by such a process, because the unit of manipulation is always the physical film strip. With help of digital image processing techniques the restoration process can be adapted for each frame or even pixel and also for many kinds of defects. This paper presents algorithms for automatic and semi-automatic defect detection and removal in digital image sequences. First an overview about typical defects in the 35 mm film domain is given. Then robust full automatic algorithms to detect dust, dirt and image vibration in noisy and disturbed environment are shown. To make expert user interaction with intermediate analysis data possible, detection and removal of defects is separated into a two step approach. Automatic algorithms for dust and dirt removal and for image sequence stabilization are presented as well as a semi-automatic algorithm for flicker and mold reduction is shown. Finally the algorithms are demonstrated and evaluated using several short film sequences.