Static background with jQuery dRawr and canvas

My work has this program that needs people to draw their answers which we have all working but now they want to be able to have a image loaded into the canvas that is able to be drawn on. Again I was able to get this worked out.

However, this image is taken and drawn into the canvas meaning when someone erases or clears the drawing the image parts get erased or cleared etc… How can I make the image static and not able to be edited? I want only what they have drawn to be editable.

here’s my example:


<div id="drawr-container" style="margin:20px;width:450px;height:450px;border:2px dotted gray;" img-src="<?php echo $response; ?>">
     <canvas id="canvas-<?php echo $modQuestions->section_num; ?>" class="question-canvas drawr-canvas"></canvas>


$(document).ready(function() {
    if($(".question-canvas").length) {
    function init_canvas1(){
        $("#drawr-container .question-canvas").drawr({
            "enable_transparency" : false,
            "canvas_width" : 800,
            "canvas_height" : 600
        $("#drawr-container .question-canvas").drawr("start");
        $("#drawr-container .question-canvas").drawr("load",$(this).parent().attr("img-src"));

$(".question-canvas").each(function(index) {
        var ctx = $(this)[0].getContext('2d');
        var img = new Image;
        if($(this).parent().attr("img-src")) {
            img.onload = function() {
                ctx.drawImage(img, 0, 0);
            img.src = $(this).parent().attr("img-src");

so this works if the response there in the img-src attribute is say “/assets/media/canvas_backgrounds/usmap.jpg” it will display the image but the user is able to edit it. I’ve searched a while now and am stumped,