var img1a = new Image();
var img2a = new Image();
var img3a = new Image();
var img4a = new Image();
var img5a = new Image();
var img1b = new Image();
var img2b = new Image();
var img3b = new Image();
var img4b = new Image();
var img5b = new Image();
img1a.src = "image/grain1.jpg";
img2a.src = "image/grain2.jpg";
img3a.src = "image/grain3.jpg";
img4a.src = "image/grain4.jpg";
img5a.src = "image/grain5.jpg";
img1b.src = "image/grain1.gif"
img2b.src = "image/grain2.gif"
img3b.src = "image/grain3.gif";
img4b.src = "image/grain4.gif";
img5b.src = "image/grain5.gif";
function cimg1a(){
  document.img1a.src=img1a.src;
}
function cimg1b(){
  document.img1a.src=img1b.src;
}
function cimg2a(){
  document.img2a.src=img2a.src;
}
function cimg2b(){
  document.img2a.src=img2b.src;
}
function cimg3a(){
  document.img3a.src=img3a.src;
}
function cimg3b(){
  document.img3a.src=img3b.src;
}
function cimg4a(){
  document.img4a.src=img4a.src;
}
function cimg4b(){
  document.img4a.src=img4b.src;
}
function cimg5a(){
  document.img5a.src=img5a.src;
}
function cimg5b(){
  document.img5a.src=img5b.src;
}