ls2filt

Transform lifting scheme to quadruplet of filters

Syntax

[LoD,HiD,LoR,HiR] = ls2filt(LS)


Description

[LoD,HiD,LoR,HiR] = ls2filt(LS) returns the four filters LoD, HiD, LoR, and HiR associated with the lifting scheme LS.

Examples

% Start from the db2 wavelet and get the
% corresponding lifting scheme.
LS = liftwave('db2')

LS = 

    'd'         [   -1.7321]    [ 0]
    'p'         [1x2 double]    [ 1]
    'd'         [         1]    [-1]
    [1.9319]    [    0.5176]      []

% Visualize the obtained lifting scheme.

displs(LS);

LS = {...                                         
'd'             [ -1.73205081]              [0]   
'p'             [ -0.06698730  0.43301270]  [1]   
'd'             [  1.00000000]              [-1]  
[  1.93185165]  [  0.51763809]              []    
};                                                

% Get the filters from the lifting scheme.

[LoD,HiD,LoR,HiR] = ls2filt(LS)

LoD =

   -0.1294    0.2241    0.8365    0.4830

HiD =

   -0.4830    0.8365   -0.2241   -0.1294

LoR =

    0.4830    0.8365    0.2241   -0.1294

HiR =

   -0.1294   -0.2241    0.8365   -0.4830

% Get the db2 filters using wfilters.
% You can check the equality.

[LoDref,HiDref,LoRref,HiRref] = wfilters('db2')

LoDref =

   -0.1294    0.2241    0.8365    0.4830

HiDref =

   -0.4830    0.8365   -0.2241   -0.1294

LoRref =

    0.4830    0.8365    0.2241   -0.1294

HiRref =

   -0.1294   -0.2241    0.8365   -0.4830