Edit in JSFiddle

<div class="wrapper">
    <img src="http://placehold.it/150x150" alt="" />
</div>

.wrapper {
    position: relative;
    width: 100%;
    height:300px;
    border: 1px solid black;
    
}

img{
    position: absolute;
    margin: auto;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
}