how to get low pass filter from image

When I am trying to run the following code, it is giving an error

[ ??? Input argument "P" is undefined. Error in ==> idealfilter at 13 H=double(D<=P); ] Please guide me to remove this error. My image size is 512*512

function idealfilter(X,P) f=imread('lena.jpg'); [M,N]=size(f); F=fft2(double(f)); u=0:(M-1); v=0:(N-1); idx=find(u>M/2); u(idx)=u(idx)-M; idy=find(v>N/2); v(idy)=v(idy)-N; [V,U]=meshgrid(v,u); D=sqrt(U.^2+V.^2); H=double(D<=P); G=H.*F; g=real(ifft2(double(G))); imshow(f),figure,imshow(g,[ ]); end

i am trying to apply low pass filter on image. is this one right code for getting low pass filter image. i want to get center point after applying low pass filter.

plz help me ...!!!!

Answer 1

[David Young]

It looks as if you didn't assign a value to the second input argument when you called the function. I also see that the first argument, X, is unused.

It seems possible you don't understand function call. If you have any doubts about how to pass values to functions, have a look at some of the introductory Matlab documentation, or a textbook, to get the idea - you'll find it very helpful to get this central idea completely clear.

By the way, this question seems closely related to your previous one, at

http://www.mathworks.com/matlabcentral/answers/587-low-pass-filter-for-image

It would be better to follow up that question rather than start a new one.