Getting Image coordinates when mouse is clicked on the image and storing it in a variable

  Hello,
  Is there any way to get the coordinates value, when an image is clicked.
Say I have created an image link using "mapedit".Instead of linking to
any URL, I want to  link to a php file, which returns a value. This value
should be stored in a file against the corresponding coordinate of the
image.
    I.e when a mouse is clicked on a image, its coordinates value should
be stored in a variable and the corresponding function should be called
which returns a variable. Both these values should be stored in a
file.

Regards
Arun