public function getImageUrl($sFile = null, $bSsl = null)
    {
        if ($sFile) {
            $sValue = $this->getConfig()->getImageUrl($this->isAdmin(), $bSsl, null, $sFile);
        } elseif (($sValue = $this->getViewConfigParam('imagedir')) === null) {
            $sValue = $this->getConfig()->getImageUrl($this->isAdmin(), $bSsl);
            $this->setViewConfigParam('imagedir', $sValue);
        }

        return $sValue;
    }