indwt

Inverse nondecimated 1-D wavelet transform

Syntax

C = indwt(W,TYPE,N)
C = indwt(W,TYPE)
C = indwt(W,TYPE,N)
X = indwt(W)
X = indwt(W,'a',0)
X = indwt(W,'ca',0)

Description

indwt performs a multilevel nondecimated 1-D wavelet reconstruction starting from a multilevel nondecimated 1-D wavelet decomposition. You can also use indwt to extract coefficients from a multilevel nondecimated 1-D wavelet decomposition.

C = indwt(W,TYPE,N) computes the reconstructed components at level N of a non-decimated 1-D wavelet decomposition. N must be a positive integer less or equal to the level of the decomposition. The valid value for TYPE is a char:

  • 'a' (or 'l' or 'A' or 'L'), which gives the low-pass component

  • 'd' (or 'h' or 'D' or 'H'), which gives the high-pass component

where 'A' (or 'L') specifies low-pass filter and 'D' (or 'H') specifies high-pass filter.

For extraction, the valid values for TYPE are the same but prefixed by 'c' or 'C'.

See ndwt for more information about the decomposition structure W.

C = indwt(W,TYPE) is equivalent to C = indwt(W,TYPE,N) with N equal to the level of the decomposition.

X = indwt(W), X = indwt(W,'a',0) or X = indwt(W,'ca',0) reconstructs the vector X based on the nondecimated 1-D wavelet decomposition structure W.

Examples

% Load the signal
load noissin;
x = noissin;

% Decompose X at level 3 using db1.
W1 = ndwt(x,3,'db1');

% Reconstruct the original signal from the 
% decomposition W1 structure.
a0 = indwt(W1,'a',0);

% Check for perfect reconstruction.
err = max(abs(x(:)-a0(:)))

err =

  8.8818e-016

% Decompose X at level 3 using db3 and periodic extension mode.
W2 = ndwt(x,3,'db3','mode','per');

% Reconstruct approximation at level 2.
a2 = indwt(W2,'a',2);

% Reconstruct detail at level 2.
d2 = indwt(W2,'d',2);

% Reconstruct detail at level 1.
d1 = indwt(W2,'d',1);

See Also

| |

Was this topic helpful?