How to trace the boundary of each object in a binary image?

I have a binary image like the following image. I want to plot the border of each object with different color. As far as I know, I need to use bwtraceboundary. But, I don't know how to choose the starting point that has to be parsed in the second input argument of bwtraceboundary. Any help is appreciated. Thanks.

Answer 1

[Matt J]

If your shapes are all solid blobs with no holes or narrow necks, then there are simpler ways than bwtraceboundary:

B=A-imerode(A,ones(3))>0;
reg=regionprops(B,'PixelList');

colors={'g','r','m','y','c'};

imagesc(A); colormap(gray(256));

hold on

for i=1:numel(reg)

      plot(reg(i).PixelList(:,1), reg(i).PixelList(:,2),['.' colors{i}]);

end

hold off

[Hsu Htet Aung]

Excuse me. I'm getting error.

% code
A=imread('cells.jpg');
B=A-imerode(A,ones(3))>0;
reg=regionprops(B,'PixelList');
colors={'g','r','m','y'};
imagesc(A); colormap(gray(256));
hold on
for i=1:numel(reg)

      plot(reg(i).PixelList(:,1), reg(i).PixelList(:,2),['.' colors{i}]);
end
hold off;
  end

    % code
  Index exceeds matrix dimensions.
Error in tttttt (line 12)
      plot(reg(i).PixelList(:,1), reg(i).PixelList(:,2),['.' colors{i}]);

[Matt J]

A=imbinarize( imread('cells.jpg') );

[Hsu Htet Aung]

Thank you

[Matt J]

You're welcome, but please Accept-click the answer to certify that it solved your problem.