Why my binary image dilation function doesn't work properly?

Question

I'm having a kind of trouble since I'm new the concept Image Analysis and the tool Matlab. What I have in my mind does not work well as lines of codes.

I'm trying to dilation function for binary images. It has to widen the given binary images.

This is my main page:

I = imread('logo_XXXX.png');
binaryImage = im2bw(I, 0.4);
s = ones(3,3,'int8');
i = dilate(binaryImage,s);
figure, imshow(i);

This is dilate.m function:

function [i] = dilate(I,s)
[Irows,Icols] = size(I);
i=I;
Itemp = I;
for row=1:Irows
    for col=1:Icols
        x = intersectAt(Itemp,s,row,col);
        if x == 1
            i(row,col)=1;
        else
            i(row,col)=0;
        end
    end
end

And this is istersectAt.m function:

function [i] = intersectAt(I,s,row,col)
[Srows,Scols] = size(s);
[Irows,Icols] = size(I);
i=0;
rowx = row - int8(Srows/2);
colx = col - int8(Scols/2);

for r=1:Srows
    for c=1:Scols
        if rowx+r <= 0 || rowx+r > Irows || colx+c <= 0 || colx+c > Icols
            continue;
        elseif I(rowx+r,colx+c) == 1 && s(r,c)==1
            i = 1;
        end
    end
end

These codes must be widen this image:

however, in some point it doesn't work properly s.t:

If you help me fix my code I would be appriciated. If you want to know about dilation you can follow this url: http://www.mathworks.com/help/toolbox/images/f18-12508.html

Matlab has this function in its library but i need to implement my own function.

Answer 1

You should avoid loops as much as possible in matlab.

If you need to write your own function just do:

s=ones(3);
i=(conv2(double(binaryImage),s,'same')>0)

From your example:

I can obtain: