Using $_GET with dots in the URL

Hello there, I’ve got a little problem (i’m sure the answer is easy, but google didn’t help)

Using the following URL: http://127.0.0.1/test.php?image.x=23&image.y=12, how can I possibly get the x and y values of ‘image’ ?

I’ve tried $_GET[‘image’], $_GET[‘image.x’], $_GET[‘image’][‘x’]… But can’t seem to find the answer, it mostly answers

Notice: Undefined index: t in…

thanks for your help !

mlk