Canvas Pixel Manipulation

JavaScript performance comparison

Revision 112 of this test case created by

Preparation code

<canvas id="canvas" height="256" width="256"></canvas>
      
<script>
Benchmark.prototype.setup = function() {
  var canvas = document.getElementById('canvas');
  var canvasWidth  = canvas.width;
  var canvasHeight = canvas.height;
  var ctx = canvas.getContext('2d');
  var imageData = ctx.getImageData(0, 0, canvasWidth, canvasHeight);
  
  var data = imageData.data;
  
  
  //var buf = new ArrayBuffer(imageData.data.length);
  var buf8 = new Uint8Array(imageData.data.length);
  var data16 = new Int16Array(imageData.data.length);
  var data16u = new Uint16Array(imageData.data.length);
  var data32 = new Uint32Array(imageData.data.length);

};
</script>

Preparation code output

<canvas id="canvas" height="256" width="256"></canvas>

Test runner

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Testing in CCBot 2.0.0 / Other 0.0.0
Test Ops/sec
8-bit Pixel Manipulation
var index = 0;
for (var y = 0; y < canvasHeight; ++y) {
    for (var x = 0; x < canvasWidth; ++x) {
        var value = (x * y) & 0xff;

        data[index]   = value;    // red
        data[index+1] = value;    // green
        data[index+2] = value;    // blue
        data[index+3] = 255;      // alpha
        index+=4;
    }
}

pending…
32-bit Pixel Manipulation
for (var y = 0; y < canvasHeight; ++y) {
    for (var x = 0; x < canvasWidth; ++x) {
        var value = x * y & 0xff;

        data32[y * canvasWidth + x] =
            (255   << 24) |    // alpha
            (value << 16) |    // blue
            (value <<  8) |    // green
             value;            // red
    }
}
pending…
16-bit Pixel Manipulation
for (var y = 0; y < canvasHeight; ++y) {
    for (var x = 0; x < canvasWidth; ++x) {
        var value = x * y & 0xff;

        data16[y * canvasWidth + x] =
            (value << 16) |    // blue
            (value <<  8) |    // green
             value;            // red
    }
}

pending…
16-bit Pixel Manipulation (unsigned)
for (var y = 0; y < canvasHeight; ++y) {
    for (var x = 0; x < canvasWidth; ++x) {
        var value = x * y & 0xff;

        data16u[y * canvasWidth + x] =
            (value << 16) |    // blue
            (value <<  8) |    // green
             value;            // red
    }
}
pending…

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