% legend11 - Laplacian Filter
clear;clc;
x=imread('Fig3.40(a).jpg');
z=im2double(x);
[a b]=size(x);
for q=1:100;
disp('enter the matrix elements : ');
for m=1:3;
    for n=1:3;
        s=input('');
        r(m,n)=s;
    end
end
disp('the filter matrix is : ');
disp(r);
t=padarray(x,[1 1],0,'both');
t=im2double(t);
for i=1:a;
    for j=1:b;
        c=[t(i:i+2,j:j+2)];
            for f=1:3;
                for g=1:3;
                    d(f,g)=c(f,g)*r(f,g);
                end
            end
         e(i,j)=sum(sum(d(1:3,1:3)));
    end
end
h=imfilter(z,r,'replicate');
if r(2,2)<0;
   e1=z-e;
   h1=z-h;
else
   e1=z+e;
   h1=z+h;
end
disp('----------------------------');
figure,imshow(x);title('original');
figure,imshow(e);title('laplacian program');
figure,imshow(h);title('laplacian imfilter');
figure,imshow(e1);title('original-laplacian program final');
figure,imshow(h1);title('original-laplacian imfilter final');    
end