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The removal of high frequencies from an image while retaining edges, is a complicated problem that has many solutions in the literature. Most of these solutions are, however, iterative and computationally expensive. In this paper, we introduce a direct method with three basic steps. In the first, the image is convolved with a Gaussian function of a defined size. In the second the gradients of the...
In this paper, the problem of iterative sharpening for local contrast enhancement is addressed. We present a fast algorithm that spreads the high frequencies of an image to successively lower resolutions resulting in an improvement in sharpness and local contrast. The algorithm is similar to the well established unsharp masking with certain fundamental differences. The image is blurred with a Gaussian...
We investigate real local isometric immersions of Kähler manifolds $${\mathbb{C}Q^2_c}$$ of constant holomorphic curvature 4c into complex projective 3-space. Our main result is that the standard embedding of $${\mathbb{C}P^2}$$ into $${\mathbb{C}P^3}$$ has strong rigidity under the class of local isometric transformations. We also prove that there are no local isometric immersions...
. A new variant of the projection method yields aperiodic tilings of the plane with some rotational symmetry. In particular we display three tilings Es with full D7-symmetry. Each of them is self similar. Further, there is an uncountable number of tilings E without any symmetry, but being almost equivalent to each of the symmetric tiling Es, i.e. for each R > 0 there is a translation T(E...
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