Removal Of Vertical Scratches In Old Movie Film By Using Wavelet Decomposition

Movie films are often damaged by aging and multiple playing, which may cause some artifacts on the films, such as dust spots,dirt,blotches,film unsteadiness,line scratches,flicker,noises,color variations and blurs. Vertical scratch is one of the artifacts we can often see. The proposed algorithm is based on the discrete binary wavelet decomposition. This transformation splits an image into approximation coefficients and horizontal and vertical detail coefficients. By analyzing the characteristics of the wavelet coefficients in the vertical line scratch regions, we give a method for detection and removal of scratch based on the modulus and angle of the gradient vector, which is also combined with the math-morphology to detect the scratch. We also improve the threshold in an algorithm based on the modulus of the horizontal wavelet coefficients, which makes this algorithm work better in scratch detection. Furthermore, we propose an algorithm in which we firstly decompose the image horizontally into several sectors, secondly we use the latter algorithm to detect scratches in these sectors separately, and thirdly we use math-morpology to combine the results together to get the position of the sractches. The experiments show this algorithm works better than the former two algorithms.The paper also compares various interpolation algorithms that reconstruct the missing data in the region of the scratch in both spactial and wavelet domains. The results show that the reconstruction in the wavelet domain can retain the high-frequency information of the image efficiently. Therefore, we choose to restore the scratch regions in the wavelet domain by...