Extract contour from an image

I have a problem about extrcting contours from an image. I need the same result that can i have if using imcontour but this command show me only the boundary of image. I tried with bwtraceboundary but i have a problem with selecting the point to start the tracing.

thanks in advance

[Image Analyst]

Attach your image so we can get an idea of what you're talking about.

[Bisca]

Thanks for the answer...I made a simple code that extract contour

clc
clear
a = imread('logo1.png');
a_gray = rgb2gray(a);
level = 0.1;
a_bw = imbinarize(a_gray,level);
Icomp = imcomplement(a_bw);
hold on
[B,L] = bwboundaries(a_bw);
imshow(label2rgb(L, @jet, [.5 .5 .5]))
%imshow(a_bw);
hold on
for k = 1:length(B)
   boundary = B{k};
   plot(boundary(:,2), boundary(:,1), 'r', 'LineWidth', 1)
end

Now, I have a doubt because i want associate coordinates in cartesian space on all point of the extrapolates contour

[Image Analyst]

You again forgot to include 'logo1.png' as requested.

I'm not sure what you're asking because boundary(:,2) is the x coordinates of the boundary/perimeter of the blob, and boundary(:,1) are the y coordinates. Why don't those give you what you want?

Answer 1

[waleed mamdouh]

clc

clear

a = imread('logo1.png');

a_gray = rgb2gray(a);

level = 0.1;

a_bw = imbinarize(a_gray,level);

Icomp = imcomplement(a_bw);

hold on

[B,L] = bwboundaries(a_bw);

imshow(label2rgb(L, @jet, [.5 .5 .5]))

%imshow(a_bw);

hold on

for k = 1:length(B)

boundary = B{k};

plot(boundary(:,2), boundary(:,1), 'r', 'LineWidth', 1)

end

Answer 2

[waleed mamdouh]

clc

clear

a = imread('logo1.png');

a_gray = rgb2gray(a);

level = 0.1;

a_bw = imbinarize(a_gray,level);

Icomp = imcomplement(a_bw);

hold on

[B,L] = bwboundaries(a_bw);

imshow(label2rgb(L, @jet, [.5 .5 .5]))

%imshow(a_bw);

hold on

for k = 1:length(B)

boundary = B{k};

plot(boundary(:,2), boundary(:,1), 'r', 'LineWidth', 1)

end