public function createResizedImageVersions($imageurl, $imageclass)
    {
        if (!$this->resizer instanceof ImageResizer) {
            throw new \LogicException('no ImageResizer available, set it using ResponsiveImageHelper::setResizer()');
        }
        $image = $this->getResponsiveImage($imageurl, $imageclass);
        $image->createResizedVersions($this->resizer);
    }