I don't know of a way to automatically extract points, but I often do this by digitizing. The method is this:
Import the graphic
Click it to open it and get the tool bar
Open the coordinates Tool.
Digitize the points of interest and copy the coordinates.
Assign them to a variable by pasting them into the notebook.
Do the same with identifiable coordinates, like the corners.
Use the corner coordinates, together with their values you read from the graph to make a RescalingTransform.
Apply the RescalingTransform to the points of interest.
Now you have a set of actual points in the graph coordinates. It's not much fun, but it works.
Regards,
David
PS. I tried to import your pdf, and Mathematica's import utility crashed. I attach a png of it which I converted with Photoshop.
Attachments:
