code: function createCanvas() {
  
  	    canvas = document.createElement('canvas');
  	    canvas.width = imageWidth;
  	    canvas.height = imageHeight;
  
  	    // Draw rectangle of a certain color covering the whole canvas area.
  	    // A JPEG image has black background by default and it might not be desirable.
  	    context = canvas.getContext('2d');
  	    context.fillStyle = options.backgroundColor || 'white';
  	    context.fillRect(0, 0, imageWidth, imageHeight);
  	}
docs: Helper to create a new canvas.