How to silhouette an image using canvas

silhouette-canvas

/* with this snippet you can create a raw silhouette of an image, it works transforming 
non-white pixels (with a small tolerance) into black pixels */

<img id="canvassource" src="your-image-300x300.jpg" />
<canvas id="area" width="300" height="300"></canvas>

<script>
    window.onload = function() {
        var canvas = document.getElementById("area");
        var context = canvas.getContext("2d");
        var image = document.getElementById("canvassource");
        context.drawImage(image, 0, 0);

        var imgd = context.getImageData(0, 0, 300, 300);
        var pix = imgd.data;
        var blackpixel = 0;
           for (var i = 0, n = pix.length; i < n; i += 4) {

            //console.log(pix[i], pix[i+1], pix[i+2]);
            if (i > 3) {
               if ((Math.abs(pix[i-3] - pix[i]) > 10) &&
                   (Math.abs(pix[i-2] - pix[i+1]) > 10) &&
                   (Math.abs(pix[i-1] - pix[i+2]) > 10)
                ) {

                   pix[i  ] = blackpixel;  
                   pix[i+1] = blackpixel;  
                   pix[i+2] = blackpixel;

               }
            }
            else {
               if (pix[i] < 250 && pix[i+1] < 250 && pix[i+2] < 250) {
                  pix[i  ] = blackpixel;  
                  pix[i+1] = blackpixel;  
                  pix[i+2] = blackpixel;
               }
         }

        }
        context.putImageData(imgd, 0, 0);       

    };
</script>