protected function mustBuildImage(File $file, $filename)
 {
     if ($this->timestampCheck == false) {
         return true;
     }
     $fs = new Filesystem();
     if (!$fs->exists($this->basePath . '/' . $filename)) {
         return true;
     }
     $info = new \SplFileInfo($this->basePath . '/' . $filename);
     if ($file->getTimestampLastChange() > $info->getCTime()) {
         return true;
     }
     // Change timestamp of the file, to mark it as "active"
     $fs->touch($this->basePath . '/' . $filename);
     return false;
 }