Instructions
Select the "System Settings" option in the PS3's main menu. A list of available settings will be shown.
Select the "Display Settings" option and you will be shown a list of available TV connections that will change the resolution ratio.
Select the connection you are using to connect the PS3 to your television. The PS3 will automatically detect which resolution ratios can be used.
Select the resolution you want to use with the PS3 and press the "X" button. Select the aspect ratio of the television you are using. Select "16:9" if you have a widescreen television. Select "4:3" for other television sets.
Press the "X" button to save the settings and the PS3's screen will shut off and turn back on with the new settings.