# How to apply distance transform on labelled matrix

2 views (last 30 days)
Rizwan Khan on 17 Jul 2020
Commented: Rizwan Khan on 21 Jul 2020
I have got a labelled matrix and want to apply distance tranform on the diffent different labels in the matrix. How can it be done in matlab?
Thanks

Show 1 older comment
Rizwan Khan on 21 Jul 2020
Dear Roberson,
I think you got my question correctly, I need the results into one matrix.
I am attaching my code and flowchart here for clearity.
CC = bwconncomp(B,8);
L = labelmatrix(CC);
num = max(L(:));
D = zeros(size(B));
for iter = 1:Inf % loop for new regions
for j= 1:num
[r,c] = find(L==j);
for k = 1:size(r,1)
D = my_dist(B(r(k,1),c(k,1)));
end
L = watershed(D);
num1(j) = max(L(:));
end
num = sum(num1);
if abs(num(iter+1)-num(iter)) == 0
break
end
end
Walter Roberson on 21 Jul 2020
is this https://ieeexplore.ieee.org/document/885672
Rizwan Khan on 21 Jul 2020

Anmol Dhiman on 20 Jul 2020
Hi Rizwan,
I am assuming the matrix as binary. You can refer to Distance Transform of a Binary Image.
Regrds,
Anmol Dhiman

Walter Roberson on 20 Jul 2020
The user specifically talks about a label matrix. Those are not binary (logical): they are numeric matrices in which each unique value defines a different region (except that 0 is always background.)
Image Analyst on 20 Jul 2020
That's why it doesn't make sense. Why on earth would you even want to try to do a distance transform on a labeled image? What would even be the formula for distance in that case? And what would he do with the result? I think this is a case of a user thinking he wants something, but he really doesn't want that, he just doesn't know it yet.
Rizwan Khan on 21 Jul 2020
Dear Image Analyst,
This is the flowchart which i need to implement in matalb.
CC = bwconncomp(B,8);
L = labelmatrix(CC);
num = max(L(:));
D = zeros(size(B));
for iter = 1:Inf % loop for new regions
for j= 1:num
[r,c] = find(L==j);
for k = 1:size(r,1)
D = my_dist(B(r(k,1),c(k,1)));
end
L = watershed(D);
num1(j) = max(L(:));
end
num = sum(num1);
if abs(num(iter+1)-num(iter)) == 0
break
end
end