CHANGING THE COLOR OF YOUR IMAGE WINDOW – â¨(AKA: PASTEBOARD) IN PHOTSOHOP
In CS5 you can change the background color that your images show up on in the image window. For example, some folks prefer to have their images surrounded by black or even white instead of the default medium gray. If you ever want to change this just press Command-K (PC: Ctrl-K) to go into Photoshop's preferences. Then click on the Interface section on the left side (second from the top) to bring up the interface preferences. Now change the Color settings for the Standard Screen Mode to whatever color you want your images to appear over.
Another way is to select the Paint Bucket tool in the toolbar. Set the desired color in the Foreground color swatch and Shift-Click in the background area to assign that color.
Or you can just right-click/control-click the background and select an option from the context menu.