How to detect corner points automatically in images ?

I have a series of images (as the figure below shows three images) where I need to get the base length of a semicircular type shape as shown in the bottom two images. I think, for this, I need to detect two corner points (at left and right as shown in the top most image) in each image. Is there any way to detect these points automatically? Here, I have attached these three images too.

Answer 1

[Image Analyst]

What you should do is to find the black boundary down to a few lines above the bottom of the image (the baseline). Then fit the coordinates to an ellipse -- see attached demo. Then evaluate the ellipse at the baseline to get the coordinates and the contact angle.

Alternatively you could use findchangepts() on the y coordinate to try to find the corners.

[Anjan Goswami]

Sir, I do not find any attached demo here.

[Image Analyst]

@Anjan Goswami, sorry, I've attached it now.