<div class="container">
  <img src="https://assets.codepen.io/5928893/masking-balloons.jpg" alt="Balloons">
</div>

<div class="container">
  <img class="one" src="https://assets.codepen.io/5928893/masking-balloons.jpg" alt="Balloons">
</div>

<div class="container">
  <img class="two" src="https://assets.codepen.io/5928893/masking-balloons.jpg" alt="Balloons">
</div>
body {
  font-family: "Benton Sans", "Helvetica Neue", helvetica, arial, sans-serif;
  margin: 2em;
}

img {
  max-width: 100%;
  display: block;
}

.container {
  width: 400px;
  height: 300px;
  margin: 1em auto;
}

.container img {
  height: 100%;
  width: 100%;
  object-fit: cover;
  -webkit-mask-size: cover;
  mask-size: cover;
}

.one {
  -webkit-mask-image: url(https://assets.codepen.io/5928893/star-mask.png);
  mask-image: url(https://assets.codepen.io/5928893/star-mask.png);
}

.two {
  -webkit-mask-image: url("https://assets.codepen.io/5928893/star-mask-gradient.png");
  mask-image: url("https://assets.codepen.io/5928893/star-mask-gradient.png");
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.