<svg width="150" height="200" viewBox="0 0 150 200">
  <filter id="brightness-shadow" filterUnits="objectBoundingBox">
    <feImage xlink:href="sky.jpg" result="sky"
      x="0" y="0" width="100%" height="100%"
      preserveAspectRatio="none"/>
    <feComponentTransfer in="sky" result="sky">
      <feFuncB type="linear" slope=" intercept=""/>
      <feFuncR id="funcR" type="linear" slope=" intercept=""/>
      <feFuncG id="funcG" type="linear" slope=" intercept=""/>
    </feComponentTransfer>
    <feGaussianBlur in="SourceAlpha" stdDeviation="2" result="blur"/>
    <feOffset in="blur" dx="4" dy="4" result="offsetBlur"/>
    <feMerge>
      <feMergeNode in="sky"/>
      <feMergeNode in="offsetBlur"/>
      <feMergeNode in="SourceGraphic"/>
    </feMerge>
  </filter>

  <g id="flower" style="filter: url(#brightness-shadow)">
    <image xlink:href="flower.svg" x="0" y="0" width="150" height="200"/>
  </g>
</svg>