Image masking

<div class="mask-right">
  <img src="image.jpg" alt="" />
</div>

.mask {
  &-right {
    mask-image: url($images-path + 'mask-right.png');
    mask-size: 100%;
    mask-repeat: no-repeat;
  }
  &-left {
    mask-image: url($images-path + 'mask-left.png');
    mask-size: 100%;
    mask-repeat: no-repeat;
  }
}