Duel Monitor Screensaver

At work I have 8 computer monitors I watch. Two of my monitors I can move open applications from one monitor to the other and work off both monitors if I need to. However one of my monitors is a little larger than the other. My screesave is rotating images I have saved in my pictures. Every 6 seconds or so a new picture will appear on one of my monitors. This is fine. My problems is on my smaller monitor the picture that displayes does not take up the entire screen. On the larger it does. There is a space above and below my pictures on the smaller monitor. Like black bars. How do I fix this?