Untitled

body {
    background: url("http://subtlepatterns.com/patterns/gray_jean.png");
    padding:0;
    height:100%;
    font-family: 'Source Sans Pro', sans-serif;
}

.side-image {
    background: url("http://www.achtergronden.info/wp-content/uploads/Natuur-Landschap-achtergrond-23.jpg");
    width: 200px;
    height: 1000px;
    float: right;
 }

<body>
    <div class="side-image">

    </div>
</body>

-webkit-mask-image: -webkit-gradient(linear, left center, right center, from(rgba(0,0,0,0)), to(rgba(0,0,0,1)))