ls2filt
Description
Examples
Compare Lifting Scheme Filters
Create a lifting scheme associated with the db4
wavelet.
wv = 'db4'; lsc = liftingScheme('Wavelet',wv);
Use ls2filt
to extract from the lifting scheme the corresponding wavelet filters. Compare with the filters generated by wfilters
. Confirm they are equal.
[lod,hid,lor,hir] = ls2filt(lsc); [lod2,hid2,lor2,hir2] = wfilters(wv); tiledlayout(2,1) nexttile stem(lod) hold on stem(lod2,"x") hold off title("Lowpass Decomposition") legend("ls2filt","wfilters",Location="northwest") nexttile stem(hid) hold on stem(hid2,"x") hold off title("Highpass Decomposition") legend("ls2filt","wfilters")
figure tiledlayout(2,1) nexttile stem(lor) hold on stem(lor2,"x") hold off title("Lowpass Reconstruction") legend("ls2filt","wfilters") nexttile stem(hir) hold on stem(hir2,"x") hold off title("Highpass Reconstruction") legend("ls2filt","wfilters",Location="northwest")
Now create a lifting scheme associated with the bior2.2
wavelet.
wv = 'bior2.2'; lsc = liftingScheme('Wavelet',wv);
Use ls2filt
to extract from the lifting scheme the corresponding wavelet filters. Compare with the filters generated by wfilters
. Observe that wfilters
includes the missing powers of the associated Laurent series as zeros so that all filters have equal even length. Except for the prepended and appended zeros, the filters coefficients generated by wfilters
equal the coefficients returned by ls2filt
.
[lod,hid,lor,hir] = ls2filt(lsc); [lod2,hid2,lor2,hir2] = wfilters(wv); fprintf('Lowpass Decomposition\n ls2filt: %s\nwfilters: %s\n', ... num2str(lod),num2str(lod2))
Lowpass Decomposition ls2filt: -0.17678 0.35355 1.0607 0.35355 -0.17678 wfilters: 0 -0.17678 0.35355 1.0607 0.35355 -0.17678
fprintf('Highpass Decomposition\n ls2filt: %s\nwfilters: %s\n', ... num2str(hid),num2str(hid2))
Highpass Decomposition ls2filt: 0.35355 -0.70711 0.35355 wfilters: 0 0.35355 -0.70711 0.35355 0 0
fprintf('Lowpass Reconstruction\n ls2filt: %s\nwfilters: %s\n', ... num2str(lor),num2str(lor2))
Lowpass Reconstruction ls2filt: 0.35355 0.70711 0.35355 wfilters: 0 0.35355 0.70711 0.35355 0 0
fprintf('Highpass Reconstruction\n ls2filt: %s\nwfilters: %s\n', ... num2str(hir),num2str(hir2))
Highpass Reconstruction ls2filt: 0.17678 0.35355 -1.0607 0.35355 0.17678 wfilters: 0 0.17678 0.35355 -1.0607 0.35355 0.17678
Input Arguments
lscheme
— Lifting scheme
liftingScheme
object
Lifting scheme, specified as a liftingScheme
object.
Output Arguments
lod,hid
— Decomposition filters
vectors
Decomposition filters associated with the lifting scheme, returned as vectors.
lod
is the lowpass decomposition filter. hid
is
the highpass decomposition filter.
Data Types: double
lor,hir
— Reconstruction filters
vectors
Reconstruction filters associated with the lifting scheme, returned as vectors.
lor
is the lowpass decomposition filter. hir
is
the highpass decomposition filter.
Data Types: double
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Version History
Introduced in R2021a
See Also
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