Gradient Image Overlay
Just simple css image overlay
HTML
<div class="one">
<img src="https://www.mtlfab.com/images/image1.png">
<img class="two" src="http://uk.palzileri.com/img/static/homepage/imgHover.png">
</div>
CSS
.one { position: relative; float: left;}
.two { position: absolute; top: 0px; left:0px; display: block;}