public function validateUploadFile($filePath) {
    $maxDimension = Mage::getStoreConfig(self::XML_NODE_PRODUCT_MAX_DIMENSION);
    $imageInfo = getimagesize($filePath);
    if (!$imageInfo) {
        Mage::throwException($this->__('Disallowed file type.'));
    }

    if ($imageInfo[0] > $maxDimension || $imageInfo[1] > $maxDimension) {
        Mage::throwException($this->__('Disalollowed file format.'));
    }

    $_processor = new Varien_Image($filePath);
    return $_processor->getMimeType() !== null;
}