Efficient optimization of inpainting scheme and line scratch detection for old film restoration

Old films usually have typical damages from dirt, scratch, and scribbling. These damages make an image degradation of vertical line scratches or blotches in frames. This paper proposes an efficient line scratch detection technique and efficient inpainting method based on MSE (mean square error) to fill the identified line scratch areas. Previous line scratch detection algorithms can only detect full column line scratches; however, we found that partial line scratch should also be identified for better film restoration. We identify line scratches using block-by-block inspection; thereby we can detect partial line scratches. After identifying the line scratches, we use a modified inpainting scheme, which uses MSE measure to compute gradient vector of the inpainting regions. In our experiment with old Korean films, we show that our scheme gives better video quality with much reduced computational complexity.