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Local Texture-Orientation

The algorithm implements a method based which makes use of the fact that a directional texture in a small picture patch shows up as a prominent spike in the fourier-transformed data (Fig. 1).

 - Texture-Direction in spatial and fourier domain -

Fig. 1:Texture directions in spatial and fourier domains

One way to detect the direction of the most prominent spike is to interpret the fourier amplitudes as a physical mass-distribution, and to search for an axis through the origin of the fourier spectrum with the minimal inertia. This can be implemented efficiently with filter operations in the spatial domain (further reference: BigŁn & Granlund, Proc. 1st Int. Conf. Comp. Vis., London 1987, 433, IEEE Computer Society Press.). In the implementation, you can choose the size of the picture area which is analyzed by changing the filter used in the calculations.

 - Examples of different filtersizes -

Fig. 2: Examples of different filtersizes (b0/b2/b4/b16)

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