An Orthogonal Family of Quincunx Wavelets with Continuously Adjustable Order
M. Feilner, D. Van De Ville, M. Unser
IEEE Transactions on Image Processing, vol. 14, no. 4, pp. 499–510, April 2005.
We present a new family of two-dimensional and three-dimensional orthogonal wavelets which uses quincunx sampling. The orthogonal refinement filters have a simple analytical expression in the Fourier domain as a function of the order λ, which may be noninteger. We can also prove that they yield wavelet bases of L2(R2) for any λ>0. The wavelets are fractional in the sense that the approximation error at a given scale a decays like O(aλ); they also essentially behave like fractional derivative operators. To make our construction practical, we propose an fast Fourier transform-based implementation that turns out to be surprisingly fast. In fact, our method is almost as efficient as the standard Mallat algorithm for separable wavelets.
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