This tutorial deals with the use, and effect, of a variable brightness mask using PhotoShop CS.  This technique uses the brightness of the pixels in the image to "scale" the amplitude, or effectiveness, of an applied filter or other image-altering tool.  This can be useful when you want to apply a modification to the dim parts of the image to a greater degree than to the brighter parts of the image, or vice-versa.  For example, if you would like to apply a Gaussian blur or an unsharp mask to the background without effecting, to a great degree, the bright stars or other bright areas of the image.

My presentation is scaled for a browser resolution of 1024 X 768.  If you are using Internet Explorer for a browser, I suggest pressing F11 before starting the tutorial.  This will allow the browser window to show the tutorial without having to use the scroll bars.  For your convenience, the Play, Pause and Time Line slider at the bottom of the screen is active.  After the tutorial finishes, press F11 again to restore the browser display to normal and then use the back button to return to this page.