ajax上传后获取文件名

I use jqueryForm and imgAreaSelect plugins for upload an image, crop it with imgAreaSelect plugin and then save. The problem is i don't know how to get file name after uploading. Sure i know how it being made and know the source, but can't access variable from upload php script.

   $(document).ready(function () {
        $(".uploadform").ajaxForm({
            target: '#viewimage',
            beforeSubmit: function () {
                $("#viewimage").html('Uploading...');
            },
            success: function () {

                $('img').imgAreaSelect({
                aspectRatio: '166:90',
                minHeight: 90,
                minWidth: 166,
                onSelectEnd: function (img, selection) {
                    $('input[name="x1"]').val(selection.x1);
                    $('input[name="y1"]').val(selection.y1);
                    $('input[name="x2"]').val(selection.x2);
                    $('input[name="y2"]').val(selection.y2);            
                    $('input[name="width"]').val(selection.x2-selection.x1);
                    $('input[name="height"]').val(selection.y2-selection.y1);     
                    $('input[name="source"]').val($(this));                     
                }});

            }
        });
    });

So the question is how i can get variable from script that used by ajax to access source to image uploaded?

UPD: Php script:

   $imagename = md5(uniqid().time()).".".$extension;
         $tmp = $_FILES['imagefile']['tmp_name'];
         if (move_uploaded_file($tmp, $filepath . $imagename)) {
         echo '<img class="preview" alt="" src="'.$filepath.'/'. 
         $imagename .'" />';

the name will be in

$_FILES['imagefile']['name']

Well this is something that helps me

$(document).ready(function () {
    $(".uploadform").ajaxForm({
        target: '#viewimage',
        beforeSubmit: function () {
            $("#viewimage").html('Uploading...');
//          showRequest;            
        },
        success: function () {
        $('img').imgAreaSelect({
//          showResponse();
            aspectRatio: '166:90',
            minHeight: 90,
            minWidth: 166,  
            onSelectEnd: function (img, selection) {
                $('input[name="x1"]').val(selection.x1);
                $('input[name="y1"]').val(selection.y1);
                $('input[name="x2"]').val(selection.x2);
                $('input[name="y2"]').val(selection.y2);            
                $('input[name="width"]').val(selection.x2-selection.x1);
                $('input[name="height"]').val(selection.y2-selection.y1);       
                $('input[name="source"]').val($('img').attr( 'src' ));
            }});

        }
    });
});