imgproxy/testdata/test1.drop-shadow.fixed.svg

<svg width="200" height="100">
  <defs>
    <filter id="dropShadow">
      <feMerge result="dsin-test"><feMergeNode  in="SourceGraphic" /></feMerge>
  <feGaussianBlur  stdDeviation="3" />
  <feOffset  dx="2" dy="1" result="dsof-test" />
  <feFlood  flood-opacity="0.8" flood-color="#0f0" />
  <feComposite in2="dsof-test" operator="in" />
  <feMerge  width="200%" height="200%">
    <feMergeNode />
    <feMergeNode in="dsin-test" />
  </feMerge>
    </filter>
  </defs>
  <rect width="200" height="100" fill="#fff"/>
  <rect x="50" y="25" width="100" height="50" fill="#f00" filter="url(#dropShadow)"/>
</svg>