public function getImageAbsolutePath()
    {
        if ($this->_imageAbsolutePath === null) {
            $this->_imageAbsolutePath = Yii::getAlias('@webroot') .
                '/' . (defined('IS_BACKEND') ? '../' : '') .
                ltrim($this->getImagePath(), '/');
            if (!file_exists($this->_imageAbsolutePath)) {
                yii\helpers\FileHelper::createDirectory($this->_imageAbsolutePath);
            }
        }
        return $this->_imageAbsolutePath;
    }