How to Slide a 3X3 window across a pixel of the image in matlab.

I have an binary image I want to slide 3*3 window across it.

Answer 1

[KALYAN ACHARJYA]

Block processing?

conv2 or imfilter all are sliding window concept.

[Nupur Goyal]

no i dont want this i want to calculate its neighbouring pixel value and check wheather its 1 or 3.

[KALYAN ACHARJYA]

The question seems easy, can you elaborate, what exactly you want?

Suppose you have binary Image, named as BW1.

[Nupur Goyal]

I have an image named BW1 of matrix 315*274 I take one pixel from it and now I want to calculate the sum its neighbouring 8 pixel and check wheather the sum is 1 or 3 and the image we take is binary image and its minimum pixel is 1 or 0.

[KALYAN ACHARJYA]

Suppose the sum is 1 or 3, then >>

after that >>

[Nupur Goyal]

if sum is 1 then >> it is ridge termination

if the sum is 3 then >>it is bifurcation

[KALYAN ACHARJYA]

[rows colm]=size(BW1);
% Avoid the boundary pixels
for i=2:rows-1;
    for j=2:colm-1
        if BW(i,j)==1
        sum_bw=sum(BW1(i-1:i+1,j-1:j+1))-1
        if sum_bw==1 | sum_bw==3
            %%Do 
        end 
        end
    end 
end

Uses of multple loops are not recomended, therefore I requested you to see working of block processing or others.

[Nupur Goyal]

can u please add one more statement to it that if the central pixel is 1 then it calculate the sum otherwise not

[KALYAN ACHARJYA]

@Nupur Edited

[Jan]

@Nupur: You are asking for trivial code. Why don't you try this by your own? Simply insert a if BW(i,j)==1.

[Nupur Goyal]

thanku i did that code its really helpful

Answer 2

[Rik]

You can still use the convolution tools:

im=randi([0 1], 315, 274);
kernel=[1 1 1;1 0 1;1 1 1];
sum_of_8=convn(im,kernel,'same');

L_bifurcation = im==1 & sum_of_8==3;
L_termination = im==1 & sum_of_8==1;

The last two variable contain the positions you are interested in.

[KALYAN ACHARJYA]

@RIK Yes +1 @Nupur referred this answer