Neanche così.
codice HTML:
.area {float: left; width: 33.33%; height: auto; position: relative; display: table;}
.area img {max-width: 100%;}
.overlay {width: 100%; height: 100%; background: rgba(0, 0, 0, 0.6); display: none; position: absolute; top: 0; left: 0; text-align: center;}
.overlay a {color: #fff; font-size: 16px; font-weight: bold; text-shadow: 1px 1px 0 rgba(0, 0, 0, 0.8); vertical-align: middle;}
.area:hover .overlay {display: table-cell;}