Define your categories as private.
Create groups.
Affect groups to users.
Grant groups access to your private categories.

Some documentation.

Last edited by tosca (2010-07-05 20:32:34)

kovacsakos wrote:

Guests should see only the titles of the categories without registration.

This is not possible as you wrote it ... but you can give them access to as special page on which you've put the list or your categories  See [extension by P@t] Additional Pages for this.

kovacsakos wrote:

I would like to give permissions  for registered members automatically to see the pictures. How can I do this?

Create a group and set it as a default group, so every new user will automatically join this group.
Grant this group access to all your categories.

If your consider you've got the answer you're seeking, please set the topic to "solved" (link under your first post)