function save_to_img(){
        var req = null;
        dataURL = document.getElementById('drawing_area_1').toDataURL("image/png");
        var url = "../html/save_to_img.php";
    
        var req = null;
        try{
            req = new XMLHttpRequest();
        } catch (ms){
            try{
                req = new ActiveXObject("Msxml2.XMLHTTP");
            } catch (nonms){
                try{
                    req = new ActiveXObject("Microsoft.XMLHTTP");
                } catch (failed){
                    req = null;
                }
            }
        }

        req.open("POST", url, true);   
        req.onreadystatechange = function(){
            switch(req.readyState) {
                case 4:
                    if(req.status == 200) {
                        window.open(url, "Save_To_Image");
                        return true;
                    } else {
                        alert(req.status + ': Serverproblem, maybe not available?');
                    }
                break;
                default:
                    return false;
                break; 
            }
        };
        
        
        req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
        req.send("img_data=" + dataURL);
    }

window.open(dataURL, "NewWindow", "width=500,height=500");