Sub-pixel vertical edge detection.

Hi.

I want to detect edge (with sub-pixel accuracy) in an image like this:

I came across a comment by Mark Ransom here where he mentions about detecting vertical edges. Since in my image, the edge isn't strictly vertical, will this be of use? It will always be roughly vertical (like in this image displayed) though. I am looking forward to an accuracy of around 1/100th of a pixel. I want to have access to these sub-pixel edge co-ordinate values.

I have tried "Accurate subpixel edge location" by Agustin Trujillo-Pino but this does not give me a continuous edge.

Are there any other algorithms available?

My image resolution will be around 600 X 1000.

Any inputs will be appreciated.

Thank you.