<svg height="0" viewBox="0 0 800 500">
  <mask id="m1" maskUnits="objectBoundingBox" maskContentUnits="objectBoundingBox">
    <path d="M0,0.05C0.03375,0.03,0.08625,0.00625,0.15125,0.0025,0.25375-0.0025,0.27375,0.04625,0.3775,0.04875c0.12125,0.0025,0.15-0.065,0.25375-0.0425,0.06125,0.0125,0.0675,0.04125,0.12625,0.055C0.84625,0.08375,0.9325,0.0425,0.99875,0V0.625L0,0.625V0.05Z" style="fill:white"/>
  </mask>
</svg>
<img src="https://placebear.com/800/500" id="test" alt="">

#test { width: 100%; height: auto; mask: url(#m1); }