Additional settings for image field

I need to add additional settings for the image in image field.

I created a checkbox and table in the database to store state:

function l_watermark_field_widget_image_image_form_alter(&$element, &$form_state, $context) {   
  if ($element['#field_name']=='field_img') {    
    foreach (element_children($element) as $key => $child) {      
      // Add the new process function to the element      
      if ($element[$key]['#type']=='managed_file' && $element[$key]['#field_name']=='field_img') {
        $element[$key]['#process'][] = 'l_watermark_image_field_widget_process';        
      }          
    }
  } 
}

function l_watermark_image_field_widget_process($element, &$form_state, $form) {   
    $attributes = array(
                         'data' => $element['#file']->fid,
                         'class' => array('l_watermark'),                         
                       );
    if (l_watermark_fid_yes($element['#file']->fid)) {
      $attributes['checked'] = 'checked';        
    }    
        
    $element['l_watermark'] = array(
      '#type' => 'checkbox',
      '#title' => t('Watermark'),
      '#default_value' => false,
      '#description' => t('Photo will be put on Watermark'),
      '#attributes' => $attributes,
    );
        
    return $element;  
}


function l_watermark_fid_yes($fid) {   
  $count = db_select('l_watermark', 'lw')
  ->condition('lw.fid', $fid)
  ->countQuery()
  ->execute()
  ->fetchField();  
  return $count;
}

in install file:

function l_watermark_schema() {
  $schema['l_watermark'] = array(
    'description' => 'The base table for l_watermark.',
    'fields' => array(
      'id' => array(
        'description' => 'The primary identifier for a l_watermark.',
        'type' => 'serial',
        'unsigned' => TRUE,
        'not null' => TRUE,
      ),
      'fid' => array(
        'description' => 'The file fid that owns this l_watermark.',
        'type' => 'int',
        'unsigned' => TRUE,
        'not null' => TRUE,        
      ),
    ),
    'primary key' => array('id'),
    'indexes' => array(
      'fid' => array('fid'),      
    ),
  ); 
  return $schema;  
} 

How can I get the value for each image, example in submite node form?

Thanks for any ideas!