gaussian-blur.html | Explore in Territory

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<title>Kraken JavaScript Benchmark: Gaussian Blur</title>
<link rel="stylesheet" href="../kraken.css">
<script>

</script>
<style> #display { border: 5px solid rgb(0,0,50);}</style>
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<body>
<div id="content">
<h2>Kraken JavaScript Benchmark: Gaussian Blur</h2>
<div id="results">
    <p>This benchmark performs a <a href="http://en.wikipedia.org/wiki/Gaussian_blur">Gaussian blur</a> on a photo.</p>
    <p><small>Photo courtesy <a href="http://www.flickr.com/photos/katclay/4296523922/in/photostream/">Kat Clay</a> from Flickr</small>.</p>
    <img id="image" src="squid.png" width="400" height="267">
    <canvas id="canvas" width="400" height="267"></canvas>
    <script>
      var sigma = 10; // radius
      var kernel, kernelSize, kernelSum;
      buildKernel();

      try {
        // Opera createImageData fix
        if (!("createImageData" in CanvasRenderingContext2D.prototype)) {
          CanvasRenderingContext2D.prototype.createImageData = function(sw,sh) { return this.getImageData(0,0,sw,sh); }
        }
      } catch(e) {}

      function buildKernel() {
        var ss = sigma * sigma;
        var factor = 2 * Math.PI * ss;
        kernel = [];
        kernel.push([]);
        var i = 0, j;
        do {
            var g = Math.exp(-(i * i) / (2 * ss)) / factor;
            if (g < 1e-3) break;
            kernel[0].push(g);
            ++i;
        } while (i < 7);
        kernelSize = i;
        for (j = 1; j < kernelSize; ++j) {
            kernel.push([]);
            for (i = 0; i < kernelSize; ++i) {
                var g = Math.exp(-(i * i + j * j) / (2 * ss)) / factor;
                kernel[j].push(g);
            }
        }
        kernelSum = 0;
        for (j = 1 - kernelSize; j < kernelSize; ++j) {
            for (i = 1 - kernelSize; i < kernelSize; ++i) {
                kernelSum += kernel[Math.abs(j)][Math.abs(i)];
            }
        }
      }

      function blurTest() {
        var results = document.getElementById('blur-result');
        results.innerHTML = "Running test...";

        window.setTimeout(function() {
          var canvas = document.getElementById('canvas');
          var ctx = canvas.getContext('2d');
          var img = document.getElementById('image')
          ctx.drawImage(img, 0, 0, img.width, img.height);

          var imgData = ctx.getImageData(0, 0, canvas.width, canvas.height);
          var width = imgData.width, height = imgData.height;
          var data = imgData.data;

          var len = data.length;
          var startTime = (new Date()).getTime();

          for (var y = 0; y < height; ++y) {
            for (var x = 0; x < width; ++x) {
              var r = 0, g = 0, b = 0, a = 0;
              for (j = 1 - kernelSize; j < kernelSize; ++j) {
                if (y + j < 0 || y + j >= height) continue;
                for (i = 1 - kernelSize; i < kernelSize; ++i) {
                  if (x + i < 0 || x + i >= width) continue;
                  r += data[4 * ((y + j) * width + (x + i)) + 0] * kernel[Math.abs(j)][Math.abs(i)];
                  g += data[4 * ((y + j) * width + (x + i)) + 1] * kernel[Math.abs(j)][Math.abs(i)];
                  b += data[4 * ((y + j) * width + (x + i)) + 2] * kernel[Math.abs(j)][Math.abs(i)];
                  a += data[4 * ((y + j) * width + (x + i)) + 3] * kernel[Math.abs(j)][Math.abs(i)];
                }
              }
              data[4 * (y * width + x) + 0] = r / kernelSum;
              data[4 * (y * width + x) + 1] = g / kernelSum;
              data[4 * (y * width + x) + 2] = b / kernelSum;
              data[4 * (y * width + x) + 3] = a / kernelSum;
            }
          }
          var finishTime = Date.now() - startTime;
          for (var i = 0; i < data.length; i++) {
              imgData.data[i] = data[i];
          }
          //imgData.data = data;
          ctx.putImageData(imgData, 0, 0);
          results.innerHTML = "Finished: " + finishTime + "ms";
        }, 10);
      }
    </script>
    <p><input type="button" value="Blur Test" onclick="blurTest();">&nbsp;<span id="blur-result"></span></p>
</div>
</div>
</body>
</html>
chromium/chrome/test/data/third_party/kraken/hosted/explanations/gaussian-blur.html
