how to show last canvas image - php

Question

im trying to find a way to only show las signature created in canvas, but the problem is that senes the img don't save in the DB i cant limit 1; like in mysqli_query or can you??
This is where the signature is created.
<div id="signArea" >
<h2 class="tag-ingo">Put signature below,</h2>
<div class="sig sigWrapper" style="height:auto;">
<div class="typed"></div>
<canvas class="sign-pad" id="sign-pad" width="300" height="100"></canvas>
</div>
</div>
<button id="btnSaveSign">Save Signature</button>
when the signature is created it call this function which saves the signature to a file :
$(document).ready(function() {
$('#signArea').signaturePad({drawOnly:true,
drawBezierCurves:true, lineTop:90});
});
$("#btnSaveSign").click(function(e) {
html2canvas([document.getElementById('sign-pad')], {
onrendered: function (canvas) {
var canvas_img_data =canvas.toDataURL('image/png');
var img_data = canvas_img_data.replace(/^data:image\/(png|jpg);base64,/, "");
//ajax call to save image inside folder
$.ajax({
url: 'save_sign.php',
data: { img_data:img_data },
type: 'post',
dataType: 'json',
success: function (response) {
window.location.reload();
}
});
}
});
});
save_sign.php
<?php
$result = array();
$imagedata = base64_decode($_POST['img_data']);
$filename = md5(date("dmYhisA"));
//Location to where you want to created sign image
$file_name = 'doc_signs/'.$filename.'.png';
file_put_contents($file_name,$imagedata);
$result['status'] = 1;
$result['file_name'] = $file_name;
echo json_encode($result);
?>
The output loads like this:
<?php
$image_list = glob("doc_signs/*.png");
foreach($image_list as $image){
?>
my problem is that it loads all images saved in the file , is there any whay to ony load last image and reset on load page??? .