<svg xmlns="http://www.w3.org/2000/svg" width="800" height="600" viewBox="0 0 800 600">
    <rect fill="#ddd" width="800" height="600"/>
    <text fill="#555" font-family="robot" dy="12" font-size="50" x="50%" y="50%" text-anchor="middle">Image 4:3</text>
  </svg>