bwtraceboundary help!

Hi,

I am trying to trace a line in a binary image in which there are many lines.

The function is based on the MATLAB standard help page for bwtraceboundary.

The function below is working great. The contour I want is detected and MATLAB overlays a green line. However the matrix that is output (named: contour) is empty apart from coordinates of the image border!

Please please can someone tell me what I seem to be missing?

Grant

Code:

I = mat2gray(~BW4);
I = im2bw(I,0.95);
imshow(I);

[x, y] = getpts;
x=round(x);
y=round(y);

s=size(I);
for t = y:1:y+50
   for u = x:1:s(2) 
      if I(t,u),
         break;
      end
   end

     contour = bwtraceboundary(I, [t, u], 'W', 4, inf,...
                                     'counterclockwise');
     if(~isempty(contour))
        hold on;
        plot(contour(:,2),contour(:,1),'g','LineWidth',2);
        hold on;
        plot(x, y,'gx','LineWidth',2);
     else
        hold on; plot(x, y,'rx','LineWidth',2);
     end

end

Answer 1

[Walter Roberson]

Using a variable named "contour" is not a good idea, as it conflicts with the name of the useful MATLAB routine "contour".

You are setting the variable "contour" inside a "for" loop. The value of "contour" at the end of the routine would be just whatever it was for the last iteration of the loop.

[Grant]

WOW! Thanks a lot! This really worked!