public function getOutputFile()
    {
        if (!$this->outputFile) {
            $dir = rtrim(dirname($this->getFile()), '/\\');
            $file = basename($this->getFile());
            $basename = substr($file, 0, strpos($file, '.'));
            $this->outputFile = $dir.'/'.$basename.'.bmp';
        }
        return $this->outputFile;
    }