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wpcoef

Wavelet packet coefficients

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    Syntax

    x = wpcoef(wpt,n)
    x = wpcoef(wpt)

    Description

    wpcoef is a one- or two-dimensional wavelet packet analysis function.

    example

    x = wpcoef(wpt,n) returns the coefficients associated with the node n of the wavelet packet tree wpt. If node n does not exist, x = [].

    x = wpcoef(wpt) is equivalent to x = wpcoef(wpt,0).

    Examples

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    Open Live Script

    Load a 1-D signal. Save the current extension mode.

    load noisdopp
x = noisdopp;
origMode = dwtmode("status","nodisp");

    Use dwtmode to change the extension mode to zero-padding. Obtain the wavelet packet tree object corresponding to the 3-level wavelet packet decomposition of the signal using the db1 wavelet. Plot the tree.

    dwtmode("zpd","nodisp")
wpt = wpdec(x,3,"db1");
plot(wpt)

    Obtain the coefficients at the node (3,0). Plot the signal and coefficients.

    cfs = wpcoef(wpt,[3 0]);
tiledlayout(2,1)
nexttile
plot(x)
title("Signal")
axis tight
nexttile
plot(cfs)
title("Packet (3,0) Coefficients")
axis tight

    Load an image. Obtain the wavelet packet tree that corresponds to a one-level wavelet packet decomposition of the image using the sym4 wavelet.

    load mask
t = wpdec2(X,1,"sym4");

    Plot the tree.

    plot(t)

    Obtain the coefficients at the node (1,0). Plot the coefficients.

    cfs = wpcoef(t,[1 0]);
figure
imagesc(cfs)
colormap(pink)
title("Packet (1,0) Coefficients")

    Restore the extension mode to the original setting.

    dwtmode(origMode,"nodisp")

    Input Arguments

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    Wavelet packet tree, specified as a wptree object.

    Node in a wavelet packet tree, specified as a nonnegative integer, or pair of nonnegative integers. See depo2ind and ind2depo.

    Example: If wpt = wpdec(1:256,2,"sym4"), then wpcoef(wpt,3) and wpcoef(wpt,[2 0]) specify the same node.

    Data Types: double

    Output Arguments

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    Node coefficients, returned as a vector or matrix.

    Data Types: double

    Version History

    Introduced before R2006a

    See Also

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    Topics