Edit in JSFiddle

<div class="container">
  <img src="https://www.w3schools.com/howto/img_fjords_wide.jpg" alt="Norway"/>
  <div class="text">Centered</div>
</div>

.container {
  position: relative;
  text-align: center;
  color: white;
}
.container img {
  width: 100%;
}
.text {
  position: absolute;
  left: 50%;
  top: 50%;
}