Abstract: A method for providing automatic brightness control in a closed loop x-ray imaging system which utilizes an automatic brightness system (ABS) sampling window. The location, size and shape of the ABS sampling window is adjusted in accordance with statistical information including spatial gray scale distribution data derived from the data related to the x-ray system and image being processed, thereby enabling the automatic brightness control to make brightness and power adjustments in accordance with statistical data from the modified ABS sampling window.