html image press enter

I guess you mean something like the below javascript example.
This will trigger the PrintImage click event everytime you press the Enter key.

function keyPressed(key)
{
  if (e.keyCode == '13')
  {
    $('#PrintImageID').click()
  }
}

if ($.browser.mozilla) {
    $(document).keypress (keyPressed);
} else {
    $(document).keydown (keyPressed);
}

$('#signinpanel').keypress(function (e) {
               if (e.keyCode == '13') {
                  // your code
               }
           });

You can handle that using jQuery or JavaScript code which ever suits your document requirement. I would try to be short, so I will use jQuery.

// upon key down
$('body').keydown(function(e) {
    // get the key code, 13 is for enter
    if(e.keyCode == 13) {
       // trigger click event to the img
       $('img').trigger('click');
    }
});

This would do it, it would check for the keydown event of the body element. And if the key pressed was Enter key, then it will trigger click event on the image element.