// Set up the image files to be used.
var fpImages = ["images/fpimg/fp1.png", "images/fpimg/fp2.png", "images/fpimg/fp3.png"];

var j = 0;
var p = fpImages.length;
var preBuffer = [];
for (i = 0; i < p; i++){
   preBuffer[i] = new Image()
   preBuffer[i].src = fpImages[i]
}
var whichImage = Math.round(Math.random()*(p-1));
function showImage(){
document.write('<img class="center_img" src="'+fpImages[whichImage]+'">');
}