The Discrete Wavelet Transform in S
نویسنده
چکیده
The theory of wavelets has recently undergone a period of rapid development. We introduce a software package called wavethresh that works within the statistical language S to perform oneand two-dimensional discrete wavelet transforms. The transforms and their inverses can be computed using any particular wavelet selected from a range of di erent families of wavelets. Pictures can be drawn of any of the oneor twodimensional wavelets available in the package. The wavelet coe cients can be presented in a variety of ways to aid in the interpretation of data. The package's wavelet transform \engine" is written in C for speed and the object-orientated functionality of S makes wavethresh easy to use. We provide a tutorial introduction to wavelets and the wavethresh software. We also discuss how the software may be used to carry out nonlinear regression and image compression. In particular, thresholding of wavelet coe cients is a method for attempting to extract signal from noise and wavethresh includes functions to perform thresholding according to methods in the literature.
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