title: Fabric.js - Tint filter
body: <p>I can't seem to get the tint filter feature of fabric.js to work, or find any example of it being used.  I have tried:</p>
  
  <pre><code>img.filters[0] = new f.Tint({
      color:'green'
  });
  </code></pre>
  
  <p>I've also tried <code>#00ff00</code> instead of <code>green</code>, but both of them just turn the image black. </p>
  
  <p>I have a number of png's that are just only black and transparent (e.g. basic shapes), and I want to be able to change the colour of them, I don't know if this is possible or not, but I figured tint sounded promising, I just can't get it to work.</p>
  
  <p>I've also tried it on photos, just turns black, and I've used other filters (like invert) in the same place in the code and it worked fine. </p>
  
  <p>Any help would be appreciated. </p>
  
  <p><strong>UPDATE:</strong>
  Full JS used, picture three just appears as a black box.</p>
  
  <pre><code>var canvas = new fabric.Canvas('c');
  var f = fabric.Image.filters;
  
  fabric.Image.fromURL('img/picture3.jpg', function(img) {
    img.set({
      left: 100,
      top: 120,
      angle: 0
    });
    img.filters[0] = new f.Tint({
        color:'00FF00'
    });
    img.applyFilters(canvas.renderAll.bind(canvas));
    canvas.add(img);
  });
  </code></pre>