function random_image() 
{ 
image_array = new Array(); 
image_array[0] = '/images/home_bg/random_photo_01.jpg'; 
image_array[1] = '/images/home_bg/random_photo_02.jpg';
image_array[2] = '/images/home_bg/random_photo_03.jpg';
image_array[3] = '/images/home_bg/random_photo_04.jpg';
image_array[4] = '/images/home_bg/random_photo_06.jpg';    

count = image_array.length; 
random = Math.floor(Math.random() * count); 

document.getElementById('content').style.backgroundImage = "url(" + image_array[random] + ")"; 
}