Vertically align an image inside div

<div class="wrap">
    <img src="http://lorempixel.com/400/200/" />
</div>

.wrap {
    height: 50px;/* max image height */
    width: 100px;
    border: 1px solid blue;
    text-align: center;
}
.wrap:before {
  content:"";
  display: inline-block;
  height: 100%;
  vertical-align: middle;
  width: 1px;
}

img {
    vertical-align: middle;
}