final protected function _createImageColorAlpha(array $rgba = array())
	{
		$keys = array('r', 'g', 'b', 'a');
		$rgba = array_filter($rgba, 'is_int');
		$rgba = array_map('abs', $rgba);
		$rgba = array_pad($rgba, count($keys), 0);
		$rgba = array_slice($rgba, 0, count($keys));
		$rgba = array_combine($keys, $rgba);

		extract($rgba);

		return imagecolorallocatealpha(
			$this->_image_handle,
			min($r, 255),
			min($g, 255),
			min($b, 255),
			min($a, 127)
		);
	}