How can I become the owner of a file/folder that root owns?

1. Open a terminal (CTRL+ALT+T). Now you are in your home.
2. sudo chown -R $USER:$USER Pictures and type your normal user password.

You can do it via terminal or gui.

GUI VERSION

Press ALT+F2 and type gksu nautilus This will turn you into an admin account using nautilus. Now go to those files and change the permissions/owner so your normal account can use them. This sometimes not work. At least for me they work and in another PC do not. Test and see.

The GUI version looks almost the same as Dash, except that instead of saying "Search" in the search bar it says "Run a command". Here is an image:

TERMINAL VERSION

Type ALT+F2 and type gnome-terminal. Go to that folder. In your case it would be cd "/home/alan/Desktop/Untitled Folder" and type sudo chown alan:alan *.jpg. This will work because it will ;)

sudo su
chown user_name folder_name

First Open your super user which is root

In the above Command user_name is the name of user on which you want to set the ownership folder_name is the folder which ownership you want to change

Command line: use Alt+F2

Change to the directory that contain your files that you want changing. Use sudo in front of your command that changes permissions, the owner and group of those files. You will be asked for your password and the command will execute as if you are root.

You could also do sudo su to enter root.

$ sudo su
[sudo] password for {username}: 
root@{host}:/home/{username}#

Then change to the directory that contain your files that you want changing.

Permission are changed with chmod Example: chmod 755 somefile would make it read, write, execute for your as the owner and read, execute for group and others. User and group are changed with chown Example: chown alan:alan somefile would make alan owner of somefile.

edit: after reading the link you posted I have a question! Did that topic not already answer your question? It talks about executing gksu nautilus. This option lets you use Nautilus as a root user. That would allow you to change access (see the picture in that topic).