Embodiments of a system that includes one or more integrated circuits are described. During operation, the system receives a sequence of video images, where a given video image in the sequence, when displayed, includes a picture portion and the non-picture portion, and where the picture portion has a histogram of brightness values. Then, the system determines the intensity setting of the light source on an image-by-image basis based on the histogram, where the light source is configured to illuminate a display that is configured to display the sequence of video images. Next, the system selectively filters changes in the intensity setting of the light source, where the selective filtering is based on a magnitude of a given change in the intensity setting from a previous video image to a current video image.