convert band pass to band reject

i've this code for band pass filter ,any one can convert it to band reject filter ??

% Bandpass Butterworth Filter

clearall;

closeall;

clc

micro = imread('grass2.jpg');

micro = double(micro);

[nx ny] = size(micro);

nx

ny

u = micro;

micro = uint8(u);

imwrite(micro,'grass5.jpg');

fftu = fft2(u,2*nx-1,2*ny-1);

fftu = fftshift(fftu);

subplot(2,2,1)

imshow(micro,[]);

subplot(2,2,2)

fftshow(fftu,'log')

% Initialize filter.

filter1 = ones(2*nx-1,2*ny-1);

filter2 = ones(2*nx-1,2*ny-1);

filter3 = ones(2*nx-1,2*ny-1);

n = 4;

fori = 1:2*nx-1

forj =1:2*ny-1

dist = ((i-(nx+1))^2 + (j-(ny+1))^2)^.5;

% Use Butterworth filter.

filter1(i,j)= 1/(1 + (dist/120)^(2*n));

filter2(i,j) = 1/(1 + (dist/30)^(2*n));

filter3(i,j)= 1.0 - filter2(i,j);

filter3(i,j) = filter1(i,j).*filter3(i,j);

end

end

% Update image with passed frequencies.

fil_micro = fftu + filter3.*fftu;

subplot(2,2,3)

fftshow(filter3,'log')

fil_micro = ifftshift(fil_micro);

fil_micro = ifft2(fil_micro,2*nx-1,2*ny-1);

fil_micro = real(fil_micro(1:nx,1:ny));

fil_micro = uint8(fil_micro);

subplot(2,2,4)

imshow(fil_micro,[])

Answer 1

[Image Analyst]

Just invert the filter. Make filter3 = 1-filter3. Try that.

[mecheal]

do u trace my code ? is it correct ? how can i identify the frequencies that included in the rejected band ??