quickly finding value of matrix

Dear everyone

I have the problem when I compute in a matrix. This problem is about the speed of computation.

I have a matrix of binary image (f), I find conected component by bwlabel in matlab. [L num]=bwlabel(f);

after that base on some property I found a vector p that include some value of L that I need to remove. this is my code and explanation

function [f,L] = clear_nontext(f,L,nontext)
% p is a vector include a lot of value we need to remove
p=find(nontext(:)~=0);
% example p= [1 2 9 10 100...] that mean we need to find in L matrix where get the value =1,2,9,10,100..] and remove it   
[a b]=size(L);
g=zeros(a,b);
for u=1:length(p)
    for i=1:a
        for j=1:b
        if L(i,j)==p(u)
            g(i,j)=1;
            %L(i,j)=500000;
            f(i,j)=0;
        end
        end
    end
end
end

When I use this way, program run but it is so slow, because with one value of p we need to check all value in matrix f (or L) again. So I need another way to run it faster. Could you help me?

Thank you so much

Answer 1

[Image Analyst]

Tran: The usual way to do it is to use ismember(). You can look in my Image Segmentation Tutorial to see how I filter away blobs, based on some criteria such as area, using ismember(). http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862