$(function() {
// OPACITY OF BUTTON SET TO 50%
$(".gallery img").css("opacity","1");

// ON MOUSE OVER
$(".gallery img").hover(function () {

// SET OPACITY TO 100%
$(this).stop().animate({
opacity: 0.8
}, "medium");
},

// ON MOUSE OUT
function () {

// SET OPACITY BACK TO 50%
$(this).stop().animate({
opacity: 1
}, "medium");
});
});