image1 = new Image();
image1.src = "images/home_nav_analysis_on.jpg";

image2 = new Image();
image2.src = "images/home_nav_pool_on.jpg";

image3 = new Image();
image3.src = "images/home_nav_commercial_on.jpg";

image4 = new Image();
image4.src = "images/home_nav_water_on.jpg";

image5 = new Image();
image5.src = "images/home_nav_makeup_on.jpg";

image6 = new Image();
image6.src = "images/home_nav_custom_on.jpg";

image7 = new Image();
image7.src = "images/home_nav_replacement_on.jpg";

// preload the big photos
var photos = new Array(3)
photos[0] = "images/home_photo_bg.gif";
photos[1] = "images/home_photo_analysis.jpg";
photos[2] = "images/home_photo_pool.jpg";
photos[3] = "images/home_photo_commercial.jpg";
photos[4] = "images/home_photo_water.jpg";
photos[5] = "images/home_photo_makeup.jpg";
photos[6] = "images/home_photo_custom.jpg";
photos[7] = "images/home_photo_replacement.jpg";

for (i=0; i < photos.length; i++) {
	var preload = new Image();
	preload.src = photos[i];
}

function swap(imageIndex) {
	document.getElementById('photo').src = photos[imageIndex];
}