public function isOCRReadable()
    {
        if (!is_dir($this->tempDir)) {
            @mkdir($this->tempDir, 0755, true);
        }

        $tempj = $this->tempDir . uniqid('captcha', true) . '.jpg';
        $tempp = $this->tempDir . uniqid('captcha', true) . '.pgm';

        $this->save($tempj);
        shell_exec("convert $tempj $tempp");
        $value = trim(strtolower(shell_exec("ocrad $tempp")));

        @unlink($tempj);
        @unlink($tempp);

        return $this->testPhrase($value);
    }