A method of scratch removal from old movie film using variant window by Hough transform

A method for removing line scratches in old movie films is proposed. This method corresponds to an adaptive median filter with a variant window. Since the film scratches appear as sharp thin lines on video images, they can be removed by median filtering. However, some fine structures of the image, especially line elements, are deformed by the median filtering. Thus, a new type of signal interpolation using a median filter with a variable window is proposed. This filter first detects the straight line element around scratches using Hough transform. If the line element is definite enough, one-dimensional median filtering is performed with a window the direction of which is the same as the straight line element. Else, usual horizontal one-dimensional median filtering is performed. By combining this filter with scratch detection, film scratches are effectively removed, without making deformation of image components. Computer simulations verify its high performance.