var exposure = 20;
var input_index = 0;
var zoom = "sm/";

function setpic() {
  $("#pic").attr("src", zoom + exposure + "/" + files[input_index]);
}

function toggle_zoom() {
  if (zoom) {
    zoom = "";
  } else {
    zoom = "sm/";
  }
}

$(function() {
  setpic();
});

Mousetrap.bind('z', function() { toggle_zoom(); setpic(); });
Mousetrap.bind('Z', function() { $("#pic").toggleClass("fit_view"); });
Mousetrap.bind('n', function() { input_index ++; setpic(); });
Mousetrap.bind('p', function() { input_index --; setpic(); });
Mousetrap.bind('b', function() { exposure ++; setpic(); });
Mousetrap.bind('d', function() { exposure --; setpic(); });