private function _paintCanvas(&$image) {
        if ($this->_params['type'] === IMAGETYPE_JPEG) {
            if (!$this->_params['crop']
                || !$this->_params['grow']
            ) {
                $this->_paintCanvasOpaque($image);
            }
        } else {
            $this->_paintCanvasTransparent($image);
        }
    }