Browsing by Autor "Alfredo Restrepo"

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    On the 2D Teager-Kaiser Operator
    (2007) Julián Quiroga; Alfredo Restrepo; Lina Wedefort; María Velasco
    The Teager-Kaiser operator is a discrete version of Teager's energy operator, advanced about 16 years ago. It is a filter of the moving window type and is commonly used as an estimator of the local energy contents of a signal; it is also used as a contrast enhancer of gray level images. We state some properties of a 2D version of the operator and its responses to common images. We characterize some of its root and preconstant images, and consider the case of separable images.
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    On the period of sums of discrete periodic signals
    (Institute of Electrical and Electronics Engineers, 1998) Alfredo Restrepo; Luis Chacon
    Unlike the continuous case, given two discrete periodic signals, their sum is always periodic. We give a characterization for the period of the sum; as shown, the least common multiple of the periods of the signals being added is not necessarily the period of the sum. Number theoretical proofs are given for the sake of rigor; examples and an interpretation in the Fourier frequency domain are given for the sake of intuition and applications.
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    Root and pre-constant signals of the 1D Teager-Kaiser operator
    (Springer Science+Business Media, 2010) Alfredo Restrepo; Julián Quiroga