frontPortfolioImg_on = new Image();
frontPortfolioImg_on.src = "images/main_portfolio_on.gif";
frontPortfolioImg_off = new Image();
frontPortfolioImg_off.src = "images/main_portfolio_off.gif";

frontAboutImg_on = new Image();
frontAboutImg_on.src = "images/main_about_on.gif";
frontAboutImg_off = new Image();
frontAboutImg_off.src = "images/main_about_off.gif";

frontContactImg_on = new Image();
frontContactImg_on.src = "images/main_contact_on.gif";
frontContactImg_off = new Image();
frontContactImg_off.src = "images/main_contact_off.gif";

subPortfolioImg_on = new Image();
subPortfolioImg_on.src = "images/sub_portfolio_on.gif";
subPortfolioImg_off = new Image();
subPortfolioImg_off.src = "images/sub_portfolio_off.gif";

subAboutImg_on = new Image();
subAboutImg_on.src = "images/sub_about_on.gif";
subAboutImg_off = new Image();
subAboutImg_off.src = "images/sub_about_off.gif";

subContactImg_on = new Image();
subContactImg_on.src = "images/sub_contact_on.gif";
subContactImg_off = new Image();
subContactImg_off.src = "images/sub_contact_off.gif";

clientLoginImg_on = new Image();
clientLoginImg_on.src = "images/client_login_on.gif";
clientLoginImg_off = new Image();
clientLoginImg_off.src = "images/client_login_off.gif";


function rollOn(imgName) {
	if(document.images) {
	    imgOn = eval(imgName + '_on.src');
	    document[imgName].src = imgOn;
	}
}

function rollOff(imgName) {
	if(document.images) {
	    imgOff = eval(imgName + '_off.src');
	    document[imgName].src = imgOff;
	}
}