<script type="text/javascript">
$(function () {
$('#btn-upload').click(function (e) {
e.preventDefault();
$('#file').click();
});
});
function changeValue(obj){
alert(obj.value);
}
</script>
<style type="text/css">
#file { display:none; }
</style>
<div>
<input type="file" id="file" name="file" onchange="changeValue(this)"/>
<button type="button" id="btn-upload">Image</button>
</div>