Find contour width in x and y through contour center point
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Hi,
How can I find the width in x and y of each contour. The width in x and y goes through the center of the contour (see image below).
Thanks.
[X,Y,Z] = peaks;
v = [1,1];
contour(X,Y,Z,v)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1148130/image.png)
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Accepted Answer
Image Analyst
on 7 Oct 2022
What kind of data do you have? A digital image with a line drawing in it? If so just use regionprops to compute the Centroid, then use find() to find the first and last line pixel at the Centroid.
mask = grayImage < 128;
mask = bwareafilt(mask, 1);
props = regionprops(mask, 'Centroid')
middleRow = round(props.Centroid(2))
middleCol = round(props.Centroid(1))
width = find(mask(middleRow, :), 1, 'last') - find(mask(middleRow, :), 1, 'first')
height = find(mask(:, middleCol), 1, 'last') - find(mask(:, middleCol), 1, 'first')
5 Comments
Image Analyst
on 8 Oct 2022
Why? What's the use case? To me it seems just like what a homework problem would be. If so, you can't turn in my code as your own so I'll give you some hints. See if you can continue it and solve it yourself:
s = load('data.mat')
x = s.xdata
y = s.ydata
plot(x, y, 'b.-', 'LineWidth', 2, 'MarkerSize', 30);
grid on;
polyin = polyshape(x, y);
[xCentroid, yCentroid] = centroid(polyin)
hold on;
plot(xCentroid, yCentroid, 'r+', 'LineWidth', 2, 'MarkerSize', 250)
figure
subplot(2, 1, 1);
plot(x, 'r.-', 'LineWidth', 2, 'MarkerSize', 30)
grid on;
yline(xCentroid, 'g', 'LineWidth', 2);
subplot(2, 1, 2);
plot(y, 'b.-', 'LineWidth', 2, 'MarkerSize', 30)
grid on;
yline(yCentroid, 'g', 'LineWidth', 2);
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