function slideSwitch() {
    var $active = $('#mainImage img.active');

    if ( $active.length == 0 ) { $active = $('#mainImage img:last'); }

    var $next = $active.next().length ? $active.next() : $('#mainImage img:first');

    $active.addClass('last-active');

    $next.css({opacity: 0.0})
        .addClass('active')
        .animate({opacity: 1.0}, 1000, function() {
            $active.removeClass('active last-active').animate({ opacity: 0.0 }, 100);
        });
}

$(document).ready(function() {
    $('#mainImage img').css( { opacity: 0.0 } );
    $('#mainImage img.active').css( {opacity: 1.0} );
    $(document).everyTime('5s', 'imageSwicth', function() { slideSwitch(); } );
});