how to run a code related to DWT and IDWT in matlab 2014a because it is giving an error Undefined function 'wfilters' for input arguments of type 'char' for [Lo_D,Hi_D,Lo_R,Hi_R] = wfilters('bior5.5');

Sir,

I am getting an error Undefined function 'wfilters' for input arguments of type 'char' for the line [Lo_D,Hi_D,Lo_R,Hi_R] = wfilters('bior5.5'); I am using matlab 2014a. My code is given below

    % %NOTE DWT demo of 2D image upto 2 level without compression

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% This script/function was created by 
% Abdullah Al Muhit
% contact - [e-mail]
% website - https://sites.google.com/site/almuhit/
% Please use it at your own risk. Also, Please cite the following paper:
% A A Muhit, M S Islam, and M Othman, “VLSI Implementation of Discrete Wavelet Transform (DWT) for Image Compression”, in Proc. of The Second International Conference on Autonomous Robots and Agents, Palmerston North, New Zealand, pp. 391-395, 2004, ISBN 0-476-00994-4. [PDF]
% A A Muhit, M S Islam, and M Othman, “ Design Design and Analysis of Discrete Wavelet Transform (DWT) for Image Compression Using VHDL”, in Proc. of the International Conference on Parallel and Distributed Processing Techniques and Applications, PDPTA 2005, Volume 1. CSREA Press 2005, pp. 157-160, Las Vegas, Nevada, USA, 2005, ISBN 1-932415-58-0. [PDF]
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

close all; clear all;
map=gray(256);

n=1:256;
x=sin((pi/64)*n)+0.01*(n-100);

% get db filter length 6
[Lo_D,Hi_D,Lo_R,Hi_R] = wfilters('bior5.5');
%figure(1);
%subplot(2,2,1); plot(Lo_D);
%subplot(2,2,2); plot(Hi_D);
%subplot(2,2,3); plot(Lo_R);
%subplot(2,2,4); plot(Hi_R);

% 1D dwt and idwt
%g = dwt(x,Lo_R);
%y = idwt(g, Lo_R);
%figure(2);
%subplot(3,1,1); plot(x);
%subplot(3,1,2); plot(g);
%subplot(3,1,3); plot(y);

% 2D dwt and idwt
imData=imread('barbara.png');
figure(3);
imshow(imData);

% first dwt
[N, M]=size(imData);
% dwt in row
dwt_row_image=zeros(N, M);
tmpData=zeros(1, M);
for i=1:N
    tmpData(1, 1:M)=imData(i, 1:M);
    tmpData(1, 1:M)=dwt(tmpData, Lo_R);
    dwt_row_image(i, 1:M)=tmpData(1, 1:M);
end

figure(4);
imshow(dwt_row_image, map);

% dwt in column
tmpData=zeros(1, N);
dwt1_imData=zeros(N, M);
for i=1:M
    tmpData(1, 1:N)=dwt_row_image(1:N, i)';
    tmpData(1, 1:N)=dwt(tmpData, Lo_R);
    dwt1_imData(1:N, i)=tmpData(1, 1:N)';
end

figure(5);
imshow(dwt1_imData, map);

%second dwt

imData=zeros(N, M);
imData(1:N, 1:M)=dwt1_imData(1:N, 1:M);
[N, M]=size(imData);
% dwt in row
dwt_row_image=zeros(N, M);
tmpData=zeros(1, M);
for i=1:N
    tmpData(1, 1:M)=dwt1_imData(i, 1:M);
    tmpData(1, 1:M)=dwt(tmpData, Lo_R);
    dwt_row_image(i, 1:M)=tmpData(1, 1:M);
end

figure(6);
imshow(dwt_row_image,map);

% dwt in column
tmpData=zeros(1, N);
dwt2_imData=dwt1_imData;
for i=1:M
    tmpData(1, 1:N)=dwt_row_image(1:N, i)';
    tmpData(1, 1:N)=dwt(tmpData, Lo_R);
    dwt2_imData(1:N, i)=tmpData(1, 1:N)';
end

figure(7);
imshow(dwt2_imData,map);

% my code for idwt

%2nd idwt
%idwt in coloumn

tmpData1=zeros(1, N);
idwt2_imData=zeros(N, M);
for i=1:M
    tmpData1(1, 1:N)=dwt2_imData(1:N, i)';
    tmpData1(1, 1:N)=idwt(tmpData1, Lo_R);
    idwt2_imData(1:N, i)=tmpData1(1, 1:N)';
end

figure(8);
imshow(idwt2_imData,map);

% idwt in row

idwt2_row_image=zeros(N, M);
tmpData1=zeros(1, M);
for i=1:N
    tmpData1(1, 1:M)=idwt2_imData(i, 1:M);
    tmpData1(1, 1:M)=idwt(tmpData1, Lo_R);
    idwt2_row_image(i, 1:M)=tmpData1(1, 1:M);
end

figure(9);
imshow(idwt2_row_image,map);

%1st idwt

%idwt in coloumn

tmpData1=zeros(1, N);
idwt1_imData=zeros(N, M);
for i=1:M
    tmpData1(1, 1:N)=idwt2_row_image(1:N, i)';
    tmpData1(1, 1:N)=idwt(tmpData1, Lo_R);
    idwt1_imData(1:N, i)=tmpData1(1, 1:N)';
end

figure(10);
imshow(idwt1_imData,map);

% idwt in row

idwt_row_image=zeros(N, M);
tmpData1=zeros(1, M);
for i=1:N
    tmpData1(1, 1:M)=idwt1_imData(i, 1:M);
    tmpData1(1, 1:M)=idwt(tmpData1, Lo_R);
    idwt_row_image(i, 1:M)=tmpData1(1, 1:M);
end

figure(11);
imshow(idwt_row_image,map);

Sir kindly help me. If possible can you give me an alternative code to replace the line "[Lo_D,Hi_D,Lo_R,Hi_R] = wfilters('bior5.5');" so that I can run the program in matlab 2014a.

Also in this code I will use a medical image specifically a brain MRI which is attached herewith.

Thanks and regards

Debarpita Chaudhuri

Answer 1

[Walter Roberson]

wfilters is part of the Wavelet Toolbox and has been for many years. You will need to license and install that toolbox.