Abstract: A power management system includes a detector (1) for generating a transition number (NI) indicating the number of transitions in a video signal (VI) during a selected period in time of the video information (VI). This is repeated in successive periods in time wherein video information (VI) is written to the same area of the display screen (6). In this way, a sequence of transition numbers (NI) occurs representing the number of transitions in the video signal (VI) for the same area of the display screen (6) in successive periods of time. A comparator (3) compares the transition numbers (NI), and a controller (4) activates a power down mode of the monitor when at least two of said transition numbers (NI) is substantially equal, which indicates that the video signal (VI) in the selected area has the same number of transitions in the different time periods, and thus, it is likely that the video signal (VI) did not change.

Abstract: In a black and white level stabilization device, an OSD signal generator (OSD-SG) generates black and white reference signals (OSD-R/G/B), amplifying circuits (VA-R/G/B) amplify the black and white reference signals (OSD-R/G/B) or RGB signals (Ri, Gi, Bi), and a measuring circuit (PNP-R/G/B, RM), coupled to the amplifying circuits (VA-R/G/B), measures a white level and a black level in response to the black and white reference signals (OSD-R/G/B).