5 papers
Rebricking frames and bases
Thomas Fink, Brigitte Forster, Florian Heinrich
In 1949, Denis Gabor introduced the ``complex signal'' (nowadays called ``analytic signal'') by combining a real function with its Hilbert transform to a complex function…
Fractional and Complex Pseudo-Splines and the Construction of Parseval Frames
Ole Christensen, Brigitte Forster, Peter Massopust
Pseudo-splines of integer order were introduced by Daubechies, Han, Ron, and Shen as a family which allows interpolation between the classical B-splines and the Daubechi…
Multigrid convergence for the MDCA-curvature estimator
Andreas Schindele, Peter Massopust, Brigitte Forster
We consider the problem of estimating the curvature profile along the boundaries of digital objects in segmented black-and-white images. We start with the curvature estimator propo…
Directional time frequency analysis via continuous frame
Ole Christensen, Brigitte Forster, Peter Massopust
Grafakos and Sansing \cite{GS} have shown how to obtain directionally sensitive time-frequency decompositions in $L^2(\mr^n)$ based on Gabor systems in $\ltr;$ the key tool is the…
Lower bounds for the approximation with variation-diminishing splines
Johannes Nagler, Paula Cerejeiras, Brigitte Forster
We prove lower bounds for the approximation error of the variation-diminishing Schoenberg operator on the interval in terms of classical moduli of smoothness depending on t…