ANAL21.rar_21AnaI_anal21

function an = anal21(data,lpf,hpf) %anal21(data,lpf,hpf) decomposes the input matrix, data, into %four subbands using filters lpf and hpf. This is a one level %decomposition. Orthonormal filter banks used with circular extension. % %This routine is used by the routine, anal2d for 2-D wavelet %decomposition. % %Author: Ajit S. Bopardikar %Copyright (c) 1998 by Addison Wesley Longman, Inc. % l = length(lpf); [m,n] = size(data); ext = [data data(:,1:l)]; %circular extension of rows ll = conv2(ext,lpf); % Low pass filtering of rows hh = conv2(ext,hpf); % High pass filtering of rows ll = ll(:, l:2:(l+n-1)); %choose the circular convolved part hh = hh(:, l:2:(l+n-1)); %and downsample by two. anr = [ll hh]'; %the row convolutions are done. ext = [anr anr(:,1:l)]; %circular extension of columns ll = conv2(ext,lpf); % Low pass filtering of columns hh = conv2(ext,hpf); % High pass filtering of columns ll = ll(:, l:2:(l+m-1)); %choose the circular convolved part hh = hh(:, l:2:(l+m-1)); %and downsample by two. an = [ll,hh]'; %One level of subband decomposition done.