Canvas getImageData() Performance

<!DOCTYPE HTML>
<html lang="en-US">
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
  <a href="javascript:go()">Begin Test</a><br />
  <canvas id="test_canvas" width="800" height="800"></canvas>
  <pre id="out"></pre>
  <script type="text/javascript">
    var out = document.getElementById('out');
    var cvs = document.getElementById('test_canvas');
    var ctx = cvs.getContext('2d');
    ctx.fillStyle = 'red';
    ctx.fillRect(10,10,790,790);

    // x, y, width, height, iterations
    var tests = [
      [10,10,1,1,100],
      [10,10,1,1,500],

      [10,10,50,50,100],
      [10,10,50,50,500],

      [10,10,780,780,10],
      [10,10,780,780,50],
    ];

    function bench(x,y,w,h,count) {
      var t = (new Date());
      for (var i=0; i < count; i++) ctx.getImageData(x,y,w,h);
      return (new Date()) - t;
    }

    function go() {
      var len = tests.length, output = [];
      for (var i=0; i < len; i++) {
        var time = bench.apply({},tests[i]);
        var mean = (time/tests[i][4]).toFixed(2);
        output.push(tests[i].toString() + ' total: ' + time + 'ms, mean: ' + mean + 'ms');
      }
      var str = navigator.userAgent + "\n" + output.join("\n");
      out.innerHTML = str;
      console.log(str);
    }

    /*
    Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.1 (KHTML, like Gecko) Chrome/14.0.835.202 Safari/535.1
    10,10,1,1,100 total: 1ms, mean: 0.01ms
    10,10,1,1,500 total: 5ms, mean: 0.01ms
    10,10,50,50,100 total: 5ms, mean: 0.05ms
    10,10,50,50,500 total: 24ms, mean: 0.05ms
    10,10,780,780,10 total: 87ms, mean: 8.70ms
    10,10,780,780,50 total: 487ms, mean: 9.74ms

    Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; ... )
    10,10,1,1,100 total: 14ms, mean: 0.14ms
    10,10,1,1,500 total: 71ms, mean: 0.14ms
    10,10,50,50,100 total: 24ms, mean: 0.24ms
    10,10,50,50,500 total: 116ms, mean: 0.23ms
    10,10,780,780,10 total: 213ms, mean: 21.30ms
    10,10,780,780,50 total: 979ms, mean: 19.58ms

    Mozilla/5.0 (Windows NT 6.1; WOW64; rv:7.0.1) Gecko/20100101 Firefox/7.0.1
    10,10,1,1,100 total: 1236ms, mean: 12.36ms
    10,10,1,1,500 total: 6087ms, mean: 12.17ms
    10,10,50,50,100 total: 1219ms, mean: 12.19ms
    10,10,50,50,500 total: 6098ms, mean: 12.20ms
    10,10,780,780,10 total: 154ms, mean: 15.40ms
    10,10,780,780,50 total: 803ms, mean: 16.06ms

    http://chart.apis.google.com/chart?chxl=1:|1x1*100|1x1*500|50x50*100|50x50*100|780x780*10|780*780*50
    &chxr=0,0,25&chxt=y,x&chbh=a&chs=440x220&cht=bvg&chco=4D89F9,C6D9FD,FF9900&chds=0,25,0,25,0,25
    &chd=t:0.1,0.1,0.05,0.05,8.7,9.74|0.14,0.14,0.24,0.23,21.3,19.58|12.36,12.17,12.19,12.2,15.4,16.06
    &chdl=C14|IE9|FF7&chdlp=t&chg=0,10&chtt=Canvas+getImageData()+Performance
    */
  </script>
</body>
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