<div class="glavniyblock" id="generalblock">
    <img src="<?=$bg;?>" style="width:1080px; height:720px;" id="generalblockimg" usemap="#girlonbalk">

<script>
var el = document.getElementById('generalblock');
function getmenu () {
    var clickX = (el.layerX == undefined ? el.offsetX : el.layerX) + 1;

    var clickY = (el.layerY == undefined ? el.offsetY : el.layerY) + 1;

    alert('Координаты клика: '+ clickX +' x '+ clickY);
}
</script>

    <map name="girlonbalk">
    <area target="" alt="" title="" href="javascript:getmenu ();" coords="109,140,102,165,114,182,114,196,97,206,89,240,97,259,100,283,94,316,109,352,113,411,115,456,103,474,134,479,151,473,140,428,146,379,164,316,159,286,155,253,166,224,161,204,140,188,150,172,147,150,137,143,128,138" shape="poly">
   </map>
</div>