public function watermark() {
		
		$args = func_get_args();

		if(!count($args)) {
			throw new ImageModifierException('Insufficient arguments for watermarking.');
		}
		
		if(!file_exists(realpath($args[0]))) {
			throw new ImageModifierException('Watermark file not found.');
		}
		
		$todo = new \stdClass();

		$todo->method		= __FUNCTION__;
		$todo->parameters	= array($args[0]);

		$this->queue[] = $todo;

	}