save line segments as binary mask

I have a skeleton stored as a set of line segments in the vector ln[x0,y0,x1,y1;...]. I can draw the skeleton on the image of size(r,c) by

   im=zeros(r,c);
   imshow(im)
   line(ln(:,[1,3])',ln(:,[2,4])','color','w','LineWidth',1);

How can I save the skeleton displayed on the image as a binary mask, with pixels on lines being 1 and everything else being 0?

Answer 1

[Guillaume]

If you have the Computer vision toolbox, you can use insertshape to draw the lines straight into your image.

If not, you can use getframe to capture the content of the figure. Unfiortunately, my experience with getframe is that it doesn't work too well and doesn't return an image the same size as you started with.

Your final option is to write your own line drawing algorithm. Bresenham's algorithm is a simple and efficient one.

[em]

I need the mask matrix, and I have line segments already, so insertshape probably doesn't apply to my case.

getframe doesn't return the same image size, like you said.

[Guillaume]

I thought you only had the endpoints of your segments, in which case, insertshape is exactly what you want. You use it to draw the lines on an blank image.