function opacity(id, opacStart, opacEnd, millisec) { 
    //speed for each frame 
    var speed = Math.round(millisec / 100); 
    var timer = 0; 

    //determine the direction for the blending, if start and end are the same nothing happens 
    if(opacStart >=1) { //Closes image	
  		setTimeout("closePic('" + id + "', " + speed + ", " + timer + ", " + opacStart + ", " + opacEnd + ")", 450);
    }else if(1 <= opacEnd){ //Opens Image
  		setTimeout("openPic('" + id + "', " + speed + ", " + timer + ", " + opacStart + ", " + opacEnd + ")", 100);
    } 
} 
function openPic(id, speed, timer, opacStart, opacEnd){
	for(i = opacStart; i <= opacEnd; i++) {
		setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed)); 
  	timer++; 
  }
} 

function closePic(id, speed, timer, opacStart, opacEnd){
	for(i = opacStart; i >= opacEnd; i--) { 			        		
  	setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed)); 
    timer++; 
	}				
}
			
//change the opacity for different browsers 
function changeOpac(opacity, id) { 			
    var object = document.getElementById(id).style; 
    object.opacity = (opacity / 100); 
    object.MozOpacity = (opacity / 100); 
    object.KhtmlOpacity = (opacity / 100); 
    object.filter = "alpha(opacity=" + opacity + ")"; 
}