Dilatometer test function

My code works for an image with the can fully on screen vertically (i.e. all the rows contain part of the can), however it currently finds the 2 edges assuming those are the only 2 points with high threshold (thats the impression i got from adrian and kieron still hasnt gotten back to me, but if it contains the entire can itl simply mean we just need to count the pixel width).

I need to experiment with the noise / the actual camera (sorry Jeremy i havent been able to take a look at the camera to try and get it working). Right now it works with the noise (+/- 10) i've set it to with the current threshold value (200) and noise-free threshold for the centre point of the line (220).