$vendors = $this->_request->getParam('vendors');

$upload = $vendorForm->vendor_photo_1->getTransferAdapter();
$upload->addValidator('Size', false, array('0kB', '2mB'));
$upload->addValidator('ImageSize', false,array('minwidth' => 350,'maxwidth' => 800,'minheight' => 350,'maxheight' => 800));
$upload->addValidator('Extension', false, array('gif', 'jpg', 'jpeg', 'png'));
...

$image=$this->_request->getParam('image');
$upload = $image->getTransferAdapter();
$upload->addValidator('Size', false, array('0kB', '2mB'));
$upload->addValidator('ImageSize', false,array('minwidth' => 350,'maxwidth' => 800,'minheight' => 350,'maxheight' => 800));
$upload->addValidator('Extension', false, array('gif', 'jpg', 'jpeg', 'png'));