Bandreject filtering on an image

How do i create a bandreject filter which i want to apply on an image ??

I want to create a bandrejectFilter of radius 10 and want to apply on an image

I know the code that i have written is wrong.Can somebody please help me with it

% Use Bandreject filter

[m,n]=size(I);

u0=256; % Cutoff frequency

u=0:m-1

v=0:n-1

if D(u,v)<266

H(u,v)==1

else H(u,v)=0

end

if D(u,v)>266

H(u,v)=1

else H(u,v)=0

end

Answer 1

[Image Analyst]

I don't understand that at all. All you're doing it some kind of strange way of intensity thresholding. Do you want to threshold a range of intensities or do a spatial frequency filter?

If you want a band reject spatial frequency filter, what I would do is to take the FFT, then call fftshift, then multiply by a black ring to zero out the stuff in the designated frequency range, then unshift and inverse fft.

[ram]

ok sorry about the previous code but i'm new in matlab hence i made a lot of mistakes

Here's the improved code

d0=centre frequency of the image

I want to reject all the frquencies betwenn 276 and 236 hence i added and subtracted 20

F1 is fftshift on fft2 of I

% Use ideal bandreject filter

[m,n]=size(I)

filter=ones(m,n);

 d0=256;

for i=1:m-1

      for j=1:n-1

          d1=((i-m)^2+(j-n)^2)^.5;

         if d1<=d0+20
         if d1>=d0-20    
             filter(i,j)=0;
         else
             filter(i,j)=1;
         end
         end
      end

end

 G=filter.*F1;
g1=abs(ifft2(G));
figure(1),imshow(g1,[])

Is this code correct ??

[Image Analyst]

No. For one thing the circle is centered at the corner instead of the middle. Also filter is the name of a built in function so you need to choose another name. And it was initialized to 1 so you don't need to do that again in the if block. Finally you can combine the two ifs into one

if d0-20 < d1 && d1 << d0+20

Of course you could vectorize it by looking at the FAQ: http://matlab.wikia.com/wiki/FAQ#How_do_I_create_a_circle.3F

[ram]

Thank you very much.Finally got it

[Saumya Verma]

Please upload the final code