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The Fourier adaptive smoothness constraint for computing optical flow on sequences of angiographic images

This paper deals with a new constraint for determining optical flow fields. This constraint is called the Fourier adaptive smoothness. It can be seen as an improvement of some existing differential techniques. It includes the magnitude image of an extended temporal Fourier transform in the smoothness constraint of the equation used for calculating the flow field. In fact a temporal window of a few frames is displaced along the sequence in order to calculate the one-dimensional corresponding Fourier transform. The resulting local magnitude image allows to constrain the smoothness of the displacement field. The authors compare on angiographic images this approach with two other well known optical flow methods wing differential techniques. A criterion is defined to allow a quantitative analysis of the results. Qualitative remarks are also given. The authors show that the constraint introduced in this paper brings better results in most cases than the two others in addition to its processing speed.