Detecting Graph paper/grids in ImageJ

[siva00x0]

Hi all!

i have a series of PDFs of EKGs that come with a standard grid. I am developing a macro for a user to be able to load the PDF and autodetect the grid. I'm using spatial calibration, and my macro consists of drawing a straight line on the grid and calibrating it to the length I need. However, is there a more automated way of detecting the grid?

Thanks!