Just some code.

        $form->addElements(array(
            new Zend_Form_Element_File('imgFile', array(
                'required'        => FALSE,
                'label'            => 'Bild uploaden',
                'destination'    => PROJECT_ROOT.'/images/userpics',
                'validators'    => array(
                    array('IsImage', TRUE),
                    array('Extension', TRUE, 'jpg,png,gif'),
                    array('ImageSize', TRUE, array('maxheight' => 80, 'maxwidth' => 80)),
                    array('Count', TRUE, 1),
                ),
                'filters'        => array(
                    array('Rename', array(
                        'target' => PROJECT_ROOT.'/images/userpics'.Zend_Auth::getInstance()->getIdentity(),
                        'overwrite' => TRUE
                    ))
                )
            )),
 
            new Zend_Form_Element_Text('imgUrl', array(
                'required'        => FALSE,
                'label'            => 'Bild-Url'
            )),
 
            new Zend_Form_Element_Submit('submit', array(
                'required'        => FALSE,
                'label'            => 'Bild speichern',
                'ignore'        => TRUE
            ))
        ));