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