filename into variable.

How would i go about building a page which could use the name of the page less .php as a variable. For example: Say I have a file called screenshot_1.php and another called screenshot_2.php . Inside each of those files I want to have code which will take the name of the file from the url and assign that value to a variable. So $picture would get the value screenshot_1 from screenshot_1.php and so on. Michael Roark