Philipp Grohs

  1. Definability and stability of multiscale decompositions for manifold-valued data.

    Authors: Philipp Grohs, Johannes Wallner
    Subjects: Differential Geometry
    Abstract

    We discuss multiscale representations of discrete manifold-valued data. As it
    turns out that we cannot expect general manifold-analogues of biorthogonal
    wavelets to possess perfect reconstruction, we focus our attention on those
    constructions which are based on upscaling operators which are either
    interpolating or midpoint-interpolating. For definable multiscale
    decompositions we obtain a stability result.

  2. Continuous Shearlet Tight Frames.

    Authors: Philipp Grohs
    Subjects: Functional Analysis
    Abstract

    Based on the shearlet transform we present a general construction of
    continuous tight frames for $L^2(\mathbb{R}^2)$ from any sufficiently smooth
    function with anisotropic moments. This includes for example compactly
    supported systems, piecewise polynomial systems, or both. From our earlier
    results it follows that these systems enjoy the same desirable approximation
    properties for directional data as the previous bandlimited and very specific
    constructions due to Kutyniok and Labate.

  3. Continuous Shearlet Frames and Resolution of the Wavefront Set.

    Authors: Philipp Grohs
    Subjects: Functional Analysis
    Abstract

    In recent years directional multiscale transformations like the curvelet- or
    shearlet transformation have gained considerable attention. The reason for this
    is that these transforms are, unlike more traditional transforms like wavelets,
    able to efficiently handle data with features along edges. The main result
    confirming this property for shearlets is contained in [G. Kutyniok, D. Labate.
    Resolution of the Wavefront Set using continuous Shearlets, Trans.

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