$(function(){
$(".zgoraj img:not(.selected)")
  
  .mouseover(function() { 
    var source = $(this).attr("src");
    $(this).attr("alt", function() { 
      return source;
    });
    source = source.replace(".png", "");
    var new_source = source+"_active.png";
    $(this).attr("src", new_source);
  })
  
  .mouseout(function() {
  var source = $(this).attr("src");
    $(this).attr("alt", function() { 
      return source;
    });
    source = source.replace("_active.png", "");
    var new_source = source+".png";
    $(this).attr("src", new_source);
  });
      
      

});