Skipping Validation for a single file in Zend_File_Transfer

For creating a business I upload 5 images along with a .csv file. I have used following zend validators

$upload = new Zend_File_Transfer();
        $upload->addValidator('Count', false, array('min' =>1, 'max' => 6))
               ->addValidator('Size', false, array('max' => '1Mb'))
               ->addValidator('ImageSize', false, array('minwidth' => 50,
                                                        'maxwidth' => 1000,
                                                        'minheight' => 50,
                                                        'maxheight' => 1000));

When I upload the CSV I get an error saying ImageSize not detected. Is there any way that I can skip ImageSize validator for .csv file?

And I figured out how to do it!!

$upload = new Zend_File_Transfer();
    $files = $upload->getFileInfo();
    foreach ($files as $fields => $contents)
    {
        if ($fields!= 'filename6')  -- Skipping the validation for csv file
        {
            $upload->addValidator('Count', false, array('min' =>1, 'max' => 6),$fields)
                   ->addValidator('Size', false, array('max' => '1Mb'),$fields)
                   ->addValidator('ImageSize', false, array('minwidth' => 50,
                                                            'maxwidth' => 1000,
                                                            'minheight' => 50,
                                                            'maxheight' => 1000),$fields);
        }
        elseif ($fields == 'filename6') -- To validate only csv file
        {
            $upload->addValidator('Extension', false, 'csv', $fields)
                   ->addValidator('Size', false, array('max' => '1Mb'),$fields);
        }
    }