SummaryBlotches are the common artifacts in degraded motion picture sequences. They are usually caused by placing dust and dirt on film surfaces as well as abrasion of film materials. Blotches are seen as dark and bright flashes spreading through the frames randomly. The spike detection index (SDIa) method is the simplest approach used to detect these artifacts. However, the drawback of SDIa method is that when the motion vectors are not precise enough in some points (e.g. in edges of moving objects) these points might be declared as blotches too. This situation can also occur in areas containing a high amount of noise. To overcome these difficulties, two post-processing methods are proposed in this paper. In the first method, the edge points are first omitted from the set of detected points and then to restore true edges, the constrained dilation algorithm is applied. In the second method, we use the local average error value in the detection process. According to low intensity variations in blotch areas, the points with relatively close intensity values are used in the averaging process. Additionally, the combination of SDIa and AR methods are proposed to be used in rather large blotch regions to achieve better detection results. Moreover, to implement the intensity interpolation stage, we propose to use adaptive block sizes to achieve better results. In this paper, a performance comparison among the available methods of detection is stated which clearly shows the superiority of the proposed methods.

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