Javascript Retina.js在数组中交换图像

我正在使用Retina.js将我网站上的图像交换为视网膜屏幕。它的工作正常，但我有一个问题，当我从阵列交换图像。我在屏幕中间有一个图像，每隔3秒就会变成一个存储在数组中的不同图像。像这样：

   <script type = "text/javascript">
          function displayNextImage() {
              x = (x === images.length - 1) ? 0 : x + 1;
              document.getElementById("img").src = images[x];
          }

          function displayPreviousImage() {
              x = (x <= 0) ? images.length - 1 : x - 1;
              document.getElementById("img").src = images[x];
          }

          function startTimer() {
              setInterval(displayNextImage, 1600);
          }

          var images = [], x = -1;

          images[0] = "smallslide2.png";
          images[1] = "smallslide3.png";
          images[2] = "smallslide4.png";
          images[3] = "smallslide5.png";
          images[4] = "smallslide1.png";
      </script>

 <p class="centeredImage">
                <img id ="img" src="smallslide1.png">
 </p>

 if (document.getElementById("img").src===smallslide1@2x.png){

    images[0] = "smallslide2@2x.png";
  images[1] = "smallslide3@2x.png";
  images[2] = "smallslide4@2x.png";
  images[3] = "smallslide5@2x.png";
  images[4] = "smallslide1@2x.png";

  }
  else {

    images[0] = "smallslide2.png";
  images[1] = "smallslide3.png";
  images[2] = "smallslide4.png";
  images[3] = "smallslide5.png";
  images[4] = "smallslide1.png";



  }