Restrict folder to certain users

So I make users upload some images and create a folder structure with their user id as a folder. Like this: for example, user 30 uploads picture 1 and 2:

uploads/clients/30/1.jpg, 2.jpg

I want to restrict access to folder 30 to user 30 and others to others.

Is it possible?

I also want to restrict access to the whole clients folder to everyone except logged in users. Is it also possible?

Thank you!