var imgcount=0;
   var imgs = 66;
   var inttime = 4000;

   // 指定の画像に差し替え
   function showimage(num) {
      var imagename = "./photos/pic" + num + ".jpg";
      document.getElementById('slideshow').src = imagename;
   }
   
   // 1番から順に表示
   function slideimage() {
      if( imgcount > imgs ) {
         imgcount = 1;
      }
      showimage( imgcount );
      imgcount++;
      slideshow.style.filter = "blendTrans(Duration=1) "; 
      slideshow.filters.blendTrans.Apply(); 
      slideshow.filters.blendTrans.Play(); 
   }

   function nextimage() {
	  imgcount++;
	  if (imgcount > imgs) {
		  imgcount= 1;
	  }
      showimage( imgcount );
	  slideshow.style.filter = "blendTrans(Duration=1) "; 
      slideshow.filters.blendTrans.Apply(); 
      slideshow.filters.blendTrans.Play(); 
   }　　　

   function backimage(){
	   imgcount--;
       if (imgcount < 1) {
		   imgcount= imgs
	   }
	   showimage( imgcount );
	   slideshow.style.filter = "blendTrans(Duration=1) "; 
       slideshow.filters.blendTrans.Apply(); 
       slideshow.filters.blendTrans.Play(); 
   }

   var slideid;
   function startshow() {
      stopshow();
      slideid = setInterval("slideimage()",inttime);
	    if (imgcount == 0) {
			imgcount= 1
	   }
   }
   
   function stopshow() {
      clearInterval(slideid);
   }