Noise Reduction Using an Undecimated Discrete
نویسنده
چکیده
A new nonlinear noise reduction method is presented that uses the discrete wavelet transform. Similar to Donoho and Johnstone, we employ thresholding in the wavelet transform domain but, following a suggestion by Coifman, we use an undecimated, shift-invariant, nonorthogonal wavelet transform instead of the usual orthogonal one. This new approach can be interpreted as a repeated application of the original Donoho and Johnstone method for diierent shifts. The main feature of the new algorithm is a signiicantly improved noise reduction compared to the original wavelet based approach, both the l 2 error and visually, for a large class of signals. This is shown both theoretically as well as by experimental results.
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