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How can I measure the length of these line segments in this image mask?

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Masood Salik
Masood Salik on 4 Feb 2021
Commented: darova on 5 Feb 2021
I have a binary image (BW_roi.mat attached) like this. And I wanted to measure the length of every line segment.
I tried the solution given in this link hough-transform. But it does not work out for me. It just measured the length of some lines as shown below.
I tried the other code
boundaries = bwboundaries(BW);
b = boundaries{patchno}; % Extract N by 2 matrix of (x,y) locations.
x = b(:, 1);
y = b(:, 2);
It though give me points (x,y) that make up these polygons. But how can I get the length of the sides of these patches?

Answers (1)

yanqi liu
yanqi liu on 5 Feb 2021
clc; clear all; close all;
load BW_ROI.mat
b = BW_roi_nodot;
b = ~b;
% measure the length of every line segment
% b([1 end],:) = 1;
% b(:,[1 end]) = 1;
b = logical(b);
b2 = imfill(b, 'holes');
b3 = b2 - b;
b3 = logical(b3);
b4 = imclose(b3, strel('disk', 5));
b5 = imopen(b2, strel('square',7));
b6 = b2 - b5;
b6 = logical(b6);
[L, num] = bwlabel(b3);
stats = regionprops(L,'ConvexHull');
figure; imshow(BW_roi_nodot); hold on;
for i = 1 : num
p = stats(i).ConvexHull;
plot(p(:,1), p(:,2),'LineWidth',2);
  1 Comment
Masood Salik
Masood Salik on 5 Feb 2021
The code directly give us the boundries of the part. We don't need further refinement.
boundaries = bwboundaries(BW_roi_nodot);
I need a code or algoritam that find the vertices of the polygons, generated by bwboundries. Then afterward I can find the lengths easily.

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