Edit in JSFiddle

<h1>box-shadow</h1>
<img class="box-shadow" src="../img/logo.png">

<h1>drop-shadow</h1>
<img class="drop-shadow" src="../img/logo.png">

img { width: 80px; }

.box-shadow {
  box-shadow: 0 0 10px black;
}
.drop-shadow {
  filter: drop-shadow(0 0 10px black);
}