Image Processing : Boundary

I am trying to obtain the boundary and measure the perimeter of of the spanner. However, it seems like there are some weird boundary selected as well (1, 2 , 10, 11). can anyone suggest me how can i get rid of the unknown boundary ? i am new to matlab image processing and i am using image analyst 's code. Below is the coding for boundary :

boundaries = bwboundaries(binaryImage,'noholes');
numberOfBoundaries = size(boundaries, 1);
for k = 1 : numberOfBoundaries
  thisBoundary = boundaries{k};
  plot(thisBoundary(:,2), thisBoundary(:,1), 'g', 'LineWidth', 2);
end

Answer 1

[soo kin wah]

Solved! bwareaopen can be used to solve this problem ;)

Answer 2

[Image Analyst]

Sorry, I didn't see that image when you originally posted it. You can also use bwareafilt() either by specifying the allowable size range, or by telling it how many blobs you want to take.