<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1000 500">
  <filter id="saturate-back">
    <feColorMatrix in="SourceGraphic" type="saturate" values="1"/>
  </filter>
  <g filter="url(#saturate-back)">
    <rect x="-3500" y="0" width="3950" height="100%" fill="green"/>
    <rect x="550" y="0" width="3950" height="100%" fill="green"/>
  </g>
  <!-- Ensure the edges of the rectangles are sharp after clamping the filter image and scaling it up -->
  <rect x="450" y="0" width="100" height="100%" fill="none" stroke="white" stroke-width="10"/>
</svg>