Help using idwt3 - high and low pass filters

1 次查看（过去 30 天）
Bran
Bran 2013-5-16
I am trying to use idwt3 on my data after applying soft thresholding but I am not sure how to do this exactly; I used dwt3(x, sym2) on my data but as I understand it in order to get back to the original displacement domain I can just use idwt3(x, sym2) I must decide low and high pass filters and input characters such as aaa etc. Is anyone well versed with this toolbox and can guide me through it
thanks bran

请先登录，再回答此问题。

回答（2 个）

Wayne King
Wayne King 2013-5-16
dwt3 returns a structure array. The 3-D wavelet coefficients are in the dec field and are ordered as explained in the documentation for dwt3.m
For example, wt.dec{1,1,1} contains the LLL subband so to construct an image approximation solely based on the the LLL image, I can set all the others to zero and invert.
X = reshape(1:64,4,4,4);
wt = dwt3(X,'sym2','mode','per');
decnew = cell(2,2,2);
decnew(:) = {zeros(2,2,2)};
decnew{1,1,1} = wt.dec{1,1,1};
wt.dec = decnew;
X1 = idwt3(wt);
  1 个评论
Bran
Bran 2013-5-17
Hi there thanks so much for your help so I am trying to use this function on a signal that is 17x17x17 which has gone through the fast fourier transform. Which would be the best parameters to use in my case? This is my code;
tmp = fftn(MAT); Adash = fftshift(tmp);
Awave=dwt3(Adash,'sym2'); Y = wthresh(Awave,'s',0.1);PLEASE NOTE! HERE IS WHERE I MADE MY ORIGINAL ERROR!!! Awaveup = idwt3(Y, 'sym2');
Adashup=ifftshift(Awaveup);
Adashup2 = ifftn(Adashup);Many thanks in advance

请先登录，再进行评论。

Bran
Bran 2013-5-16
Hi there thanks so much for your help so I am trying to use this function on a signal that is 17x17x17 which has gone through the fast fourier transform. Which would be the best parameters to use in my case? This is my code;
tmp = fftn(MAT); Adash = fftshift(tmp);
Awave=dwt3(Adash,'sym2');
Y = wthresh(Awave,'s',0.1);
PLEASE NOTE! HERE IS WHERE I MADE MY ORIGINAL ERROR!!! Awaveup = idwt3(Y, 'sym2');
Adashup=ifftshift(Awaveup);
Adashup2 = ifftn(Adashup);
Many thanks in advance

类别

在 Help Center 和 File Exchange 中查找有关 Discrete Multiresolution Analysis 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by