| <svg style="display: block; width: 0; height: 0"> |
| <defs> |
| <filter id="grayscale"> |
| <feColorMatrix type="matrix" values="0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0 0 0 1 0"/> |
| </filter> |
| </defs> |
| </svg> |
| <canvas id="canvas" width="100" height="100"></canvas> |
| <script> |
| var canvas = document.getElementById('canvas'); |
| var ctx = canvas.getContext('2d'); |
| ctx.filter = 'url(#grayscale)'; |
| ctx.fillStyle = '#0f0'; |
| ctx.fillRect(20, 20, 20, 20); |
| var filter = document.getElementById('grayscale'); |
| filter.parentNode.removeChild(filter); |
| ctx.fillRect(60, 20, 20, 20); |
| </script> |