Applying analysis filter bank to get even length of low pass and odd length pass filter

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faraz.a 2013-8-4

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/83951-applying-analysis-filter-bank-to-get-even-length-of-low-pass-and-odd-length-pass-filter

I have an image i have to apply the 1‐D (5,3)(to each row (pixel values) of the image)analysis filter bank with the (1,2) normalization (i.e., DC gain of 1 for the low‐pass filter and Nyquist gain of 2 for the high‐pass filter). Then i have to get L subband consists of the even samples (starting with sample zero) and the H subband consists of the odd samples.

I got this code online but it says it has even subbands for both low and high pass filter. can anyone tell me how to apply the above analysis filter bank(5,3).

function [lo, hi] = afb(x, af)
% [lo, hi] = afb(x, af)
%
% Analysis filter bank
% x -- N-point vector (N even); the resolution should be 2x filter length
%
% af  -- analysis filters
% af(:, 1): lowpass filter (even length)
% af(:, 2): highpass filter (even length)
%
% lo: Low frequency
% hi: High frequency
%
 N = length(x);
L = length(af)/2;
x = cshift(x,-L);
 % lowpass filter
lo = upfirdn(x, af(:,1), 1, 2);
lo(1:L) = lo(N/2+[1:L]) + lo(1:L);
lo = lo(1:N/2);
 % highpass filter
hi = upfirdn(x, af(:,2), 1, 2);
hi(1:L) = hi(N/2+[1:L]) + hi(1:L);
hi = hi(1:N/2);