Custom field displayed based on author node I have a website for ads. In addition the user will have opportunity to make his ad as a VIP ad. 

When the user creates a new ad, down bellow will be displayed a field "Make your ad VIP" and after clicking on that button it will popup a description. 
This field is created as custom field with Display suite, but I want to make visible only on node author. 

The idea is only user that is author of the node can see that field "Make your ad VIP".

The module "Field permissions" cannot control this custom field.

EDIT:

The field name is "adding_make_vip", the custom module is "custom_alter" and this is the code that I've tried:

&lt;?php

function custom_alter_field_access($op, $field, $entity_type, $entity, $account) {
  global $user;
  if ($op == 'view' &amp;&amp; !empty($entity) &amp;&amp; $field['field_name'] == 'adding_make_vip') {

   // $entity will be the node,so check node author with current user.
   if($entity-&gt;uid == $user-&gt;uid) {
      return TRUE;
    } 
   else {
    return FALSE;
    }
  }
}


Unfortunately it didn't hide the field for anonymous users and users that aren't authors of the node.
How about implementing hook_field_access() in your custom module.

This hook takes operation edit/view as parameters and returns access to the user for the operations.As a sample code 

function MYMODULE_field_access($op, $field, $entity_type, $entity, $account) {
  global $user;
  if ($op == 'view' &amp;&amp; !empty($entity) &amp;&amp; $field['field_name'] == 'your_field_name') {

   // $entity will be the node,so check node author with current user.
   if($entity-&gt;uid == $user-&gt;uid) {
      return TRUE;
    } 
   else {
    return FALSE;
    }
  }
}