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lwt2

2-D lifting wavelet transform

Syntax

Description

lwt2 performs a 2-D lifting wavelet decomposition with respect to a particular lifted wavelet that you specify.

[CA,CH,CV,CD] = lwt2(X,W) computes the approximation coefficients matrix CA and detail coefficients matrices CH, CV, and CD, obtained by a lifting wavelet decomposition, of the matrix X. W is a lifted wavelet name (see liftwave).

X_InPlace = lwt2(X,LS) computes the approximation and detail coefficients. These coefficients are stored in place:

CA = X_InPlace(1:2:end,1:2:end)

CH = X_InPlace(2:2:end,1:2:end)

CV = X_InPlace(1:2:end,2:2:end)

CD = X_InPlace(2:2:end,2:2:end)

lwt2(X,W,LEVEL) computes the lifting wavelet decomposition at level LEVEL.

X_InPlace = lwt2(X,W,LEVEL,'typeDEC',typeDEC) or [CA,CH,CV,CD] = LWT2(X,W,LEVEL,'typeDEC',typeDEC) with typeDEC = 'w' or 'wp' computes the wavelet or the wavelet packet decomposition using lifting, at level LEVEL.

Instead of a lifted wavelet name, you may use the associated lifting scheme LS: lwt2(X,LS,...) instead of LWT2(X,W,...).

For more information about lifting schemes, see lsinfo.

Examples

Algorithm

This function implements the polyphase algorithm.

lwt reduces to dwt with zero-padding extension mode and without extra-coefficients.

See Also

ilwt2

References

Strang, G.; T. Nguyen (1996), Wavelets and filter banks, Wellesley-Cambridge Press.

Sweldens, W. (1998), "The Lifting Scheme: a Construction of Second Generation of Wavelets," SIAM J. Math. Anal., 29 (2), pp. 511-546.


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