function dataURLtoBlob(data_url) {
			var arr = data_url.split(','), mime = arr[0].match(/:(.*?);/)[1],
			bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);
			while(n--){
			u8arr[n] = bstr.charCodeAt(n);
			}
			return new Blob([u8arr], {type:mime});
	}