A simple LESS approach for a reusable high-DPI media query.

reusable-high-dpi.less

@highDPI: ~"only screen and (-webkit-min-device-pixel-ratio: 1.5), only screen and (min-resolution: 1.5dppx)";

div {
  background-image: url('1x.png');
  @media @highDPI {
    background-image: url('2x.png');
    background-size: 100px 100px; /* The original 1x dimensions. */
  }
}