denoise: Wavelet-based Denoising

View source: R/denoise.R

denoiseR Documentation

Wavelet-based Denoising

Description

Denoise the signal x using the 2-band wavelet system described by the filter h using either the traditional discrete wavelet transform (DWT) or the linear shift invariant discrete wavelet transform (also known as the undecimated DWT (UDWT)).

Usage

denoise(x, h, type, option)
denoise.dwt(x, h, option = default.dwt.option)
denoise.udwt(x, h, option = default.udwt.option)

Arguments

x

1D or 2D signal to be denoised

h

numeric scalar specifying scaling filter to be applied

type

type of transform. Valid values are:

DWT.TRANSFORM.TYPE
UDWT.TRANSFORM.TYPE
option

list containing desired transformation settings

Details

The transformation settings in the option list are:

threshold.low.pass.part:

logical scalar. If TRUE, threshold the low-pass component.

threshold.multiplier:

thld = c*MAD(noise_estimate)

variance.estimator:

Valid values are:

MAD.VARIANCE.ESTIMATOR Mean absolute deviation
STD.VARIANCE.ESTIMATOR Classical numerical std estimate
threshold.type:

Valid values are:

SOFT.THRESHOLD.TYPE Soft thresholding
HARD.THRESHOLD.TYPE Hard thresholding
num.decompression.levels:

number of levels in wavelet decomposition. Setting this to MAX.DECOMPOSITION will allow maximal decomposition.

threshold:

actual threshold to use. Setting this to anything but CALC.THRESHOLD.TO.USE will disable the variance.estimator setting.

Value

Returns a list with components:

xd

estimate of noise free signal

xn

estimated noise signal (x-xd)

option

list of actual parameters used. It is configured the same way as the input option list with an additional element - option[[7]] = type.

Note

Both denoise.dwt and denoise.udwt are convenience routines that call the denoise routine with appropriate default arguments.

Author(s)

P. Roebuck proebuck1701@gmail.com

Examples

sig <- makesig(SIGNAL.DOPPLER)
h <- daubcqf(6)
ret.dwt <- denoise.dwt(sig$x, h$h.0)

rwt documentation built on June 14, 2022, 5:07 p.m.

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