With the emergence of advanced display media as well as digital video coding and compression schemes came a variety of new video formats including program content dependent formats, as proposed by the Grand Alliance for their high definition television (HDTV) standard. Digital video down-conversion is a low complexity quality reduction task, whereas the more complex video up-conversion incorporates a tradeoff between computational cost and perceptual quality. Motion-compensated conversion algorithms have the potential for good results, but go in hand with a computational complexity disadvantage, whereas motion-adaptive interpolation methods constitute a compromise between the extremes. This paper presents a general motion-adaptive format conversion approach based on a multiresolution decomposition and nonlinear subband interpolation filtering. The class of Ll permutation filters feature a flexible, input-signal dependent behavior by exploiting the order statistics of an input signal. In this paper, such an approach is utilized for interpolation purposes, applicable to any arbitrary format conversion problem. A successful application of Ll filter based interpolators in combination with a hierarchical multiresolution decomposition as a motion-adaptive format conversion method is presented. As an evaluation of performance, two format conversion case studies are presented, namely deinterlacing for progressive display media and frame-rate up-conversion for the reduction of temporal artifacts.
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