Form Image/Submit handling?

[clumsy]

I have a basic login form, method:post, action is PHP_SELF.. However my login submit button is a <INPUT TYPE="Image" NAME="login"> tag.. Now when this is clicked I have PHP code that checks for isset($login).. However it doesn't recognize this variable when the image is clicked.. I'm not sure what needs to be done for PHP to handle this type of submission..
If anyone has any suggestions, webpage resources I could look at or anything else that might help that would be great..

Thanks,

[Anon]

when using images, the variables to check would be:

$login_x and $login_y

and try:
if($login_x and $login_y){

that may work.

[clumsy]

Detecting those variables did the trick, thank you.