How to apply lifting wavelet transform on image fusion

close all;clear;clc

%% Read Images

%% the size of images must be equal

a=imread("CT_Image2.jpg");

a=rgb2gray(a);

a=imresize(a,[276,276]);

b=imread("MRI_Image.jpg");

b=rgb2gray(b);

b=imresize(b,[276,276]);

%% Wavelet Transform

lscheme = liftingScheme('Wavelet','bior3.7');

[a1,b1,c1,d1]=lwt2(a,'LiftingScheme',lscheme,'Level',2);

%a1 is approximate coefficient matrix

%b1,c1,d1 are detail horizontal,vertical and diagonal coefficient matrix respectively

[a2,b2,c2,d2]=lwt2(b,'LiftingScheme',lscheme,'Level',2);

%a2 is approximate coefficient matrix

%b2,c2,d2 are detail horizontal,vertical and diagonal coefficient matrix respectively

[k1,k2]=size(a1);

%% Fusion Rules

a3 = zeros([k1 k2]);%preallocating with zeros

%% Average Rule

for i=1:k1

for j=1:k2

a3(i,j)=(a1(i,j)+a2(i,j))/2;

end

end

%% Max Rule

b3 = zeros([k1 k2]);%preallocating with zeros

c3 = zeros([k1 k2]);%preallocating with zeros

d3 = zeros([k1 k2]);%preallocating with zeros

for i=1:k1

for j=1:k2

b3(i,j)=max(b1(i,j),b2(i,j));

c3(i,j)=max(c1(i,j),c2(i,j));

d3(i,j)=max(d1(i,j),d2(i,j));

end

end

%% Inverse Wavelet Transform

c=ilwt2(a3,b3,c3,d3,'LiftingScheme',lscheme,'Level',2);

I have apply lifting scheme on image fusion .However, have error come out for max rule, how to fix this problem?

[Sharmin Kibria]

Hi Nutveesa,

The error is coming from b3(i,j)=max(b1(i,j),b2(i,j));

b1 and b2 are cell arrays. The entries b1(i,j) and b2(i,j) are cell arrays as well. max cannot operate on cell arrys directly and is erroring out. Modify the command to this:

b3{i,j}=max(b1{i,j},b2{i,j});

Also, for ilwt2 to work correctly b3,c3,d3 must be cell arrays. So you need to initialize them as b3 = cell(k1,k2);

I hope it fixes the issue.

Thanks

Sharmin