Convert contour to broken line in image Matlab

Question

I have the following problem in Matlab: I have a 2D closed contour (a set of 2D coordinates of points) representing an object like in this image:

I want to convert it into a broken line contour like: dot-line-space-dot-line-space, etc.

Is there a way to solve this problem in Matlab? Thank you very very much

Answer 1

You can first fill in the object using imfill, then trace it using bwboundaries, and plot the result using plot with a given line style.

% Load the image in and convert to binary
img = imread('https://i.stack.imgur.com/G4NLh.png');
img = img(:,:,1) > 170;

% Fill in the middle hole and compute the boundary
boundary = bwboundaries(imfill(img, 'holes'));

% Plot the boundary on a black background
plot(boundary{1}(:,2), boundary{1}(:,1), ...
            'LineStyle', '-.', ...
            'Marker', 'none')

axis image
axis ij

Update

Oh...you already have the x/y points. Oh well! Just use the LineStyle property of plot to accomplish what you want.