Edit in JSFiddle

$(function() {
// vertical align function
$.fn.vAlign = function() {
    return this.each(function(i){
        var ah = $(this).height();
        var ph = $(this).parent().height();        
        var mh = Math.ceil((ph-ah) / 2); 
        $(this).css('margin-top', mh);
    });
};

$('.greenBorder img').vAlign();
//
});

<div class="greenBorder">
    <img src="http://gawebdev.com/georgia-web-development/wp-content/uploads/2012/12/page_css_128.png?f35187" alt="" title="" border="0" />            
</div>

.greenBorder{
    border: 1px solid green;
    height: 278px;
    width: 446px;
    text-align:center;
}