MATLAB: How to get the coordinates from a certain image.

Question

Hi, I have some problems about getting all the coordinates from a certain image, the code I use is following:

R = imread('B1slicer.jpg');
[C,handle] = imcontour(R);
x = C (1,:);
y = C(2,:);
[K,V] = convhull(x,y);
plot (x,y,'+b',x(K),y(K),'-r');

However, there are some extra points getting extracted, and I donnot know how to solve this problem.

Is there any other methods to solve this problem?

Thanks.

Answer 1

You can use the inequalities and remove them from the points.

idx = y<200 ; 
x(idx) = [] ; y(idx) = [] ;

Also you can use below:

I = imread('B1slicer.jpg') ; 
[y,x] = find(I) ;