You can do it this way:
.container{
position: relative;
width: 100px;
height: 100px;
overflow: hidden;
z-index: 1;
}
img{
left: 50%;
position: absolute;
top: 50%;
-ms-transform: translate(-50%, -50%);
-webkit-transform: translate(-50%, -50%);
-moz-transform: translate(-50%, -50%);
transform: translate(-50%, -50%);
max-width: 100%;
}