function random_img(){

	var rn = Math.floor(Math.random()*image.length)
	  if (rn == 0){
	     rn = 1;
	  }
	     return rn;
	     
}
	
	var image=new Array()
  	//specify random images below.
  	image[1] = "http://sgcity.org/leisure/assets/images/header/header_dino_dinokids.png";
	
//run this function on window.onload
function runPhotoLoad(){
	//run function
	var rn = random_img();
	//display image
	document.getElementById("header_photo").innerHTML = '<img src="' + image[rn] +'">';
}