Mathematics of adaptive wavelet transforms: relating continuous with   discrete transforms

Harold H. Szu; Brian A. Telfer

doi:10.1117/12.173205

1 July 1994 Mathematics of adaptive wavelet transforms: relating continuous with discrete transforms

Harold H. Szu, Brian A. Telfer

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Optical Engineering, Vol. 33, Issue 7, (July 1994). https://doi.org/10.1117/12.173205

Abstract

We prove several theorems and construct explicitly the bridge between the continuous and discrete adaptive wavelet transform (AWT). The computational efficiency of the AWT is a result of its compact support closely matching linearly the signal's time-frequency characteristics, and is also a result of a larger redundancy factor of the superposition-mother s(x) (super-mother), created adaptively by a linear superposition of other admissible mother wavelets. The super-mother always forms a complete basis, but is usually associated with a higher redundancy number than its constituent complete orthonormal (CON) bases. The robustness of super-mother suffers less noise contamination (since noise is everywhere, and a redundant sampling by bandpassings can suppress the noise and enhance the signal). Since the continuous super-mother has been created off-line by AWT (using least-mean-squares neural nets), we wish to accomplish fast AWT on line. Thus, we formulate AWT in discrete high-pass (H) and low-pass (L) filter bank coefficients via the quadrature mirror filter (QMF), a digital subband lossless coding. A linear combination of two special cases of the complete biorthogonal normalized (Cbi-ON) QMF [L(z),H(z),L⁺(z),H⁺(z)], called α-bank and β-bank, becomes a hybrid aα + bβ-bank (for any real positive constants a and b) that is still admissible, meaning Cbi-ON and lossless. Finally, the power of AWT is the implementation by means of wavelet chips and neurochips, in which each node is a daughter wavelet similar to a radial basis function using dyadic affine scaling.

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Harold H. Szu and Brian A. Telfer "Mathematics of adaptive wavelet transforms: relating continuous with discrete transforms," Optical Engineering 33(7), (1 July 1994). https://doi.org/10.1117/12.173205

Published: 1 July 1994

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