var image = new Array();
image[0] = "url(./img/main_peripheral_a.jpg)";
image[1] = "url(./img/main_peripheral_b.jpg)";
image[2] = "url(./img/main_peripheral_c.jpg)";

function chImage(){
	x = Math.floor(Math.random() * image.length);
	document.getElementById("main_peripheral_top").style.backgroundImage = image[x];
}