How to get a single line on an image?

I'm trying to make a little bit of image analysis software. I need to plot the intensity of pixels lying along a user selected line. This would be a lot easier if I could have a function which returns the coordinates of the line, but would allow me to see what line is being selected as I'm clicking, and which would not allow me to define a long curve.

Answer 1

[Iain]

Oh, I just found the perfect answer. imline.