Masking on a projection screen used in a front projection video display refers to placing objects of some sort (usually cloth) over parts of the screen which are not needed depending on the aspect ratio of the program material being displayed. For instance, on a “wide” screen with a 16-by-9 aspect ratio, widescreen movies will fill the entire screen. However, traditional television program material recorded in the nearly square 4-by-3 format will leave blank space on the screen to the edges (since its height will fill the height of the screen but its width will not be as wide as the wider 16-by-9 aspect ratio screen). Masking entails covering up the unused portions of the screen to the left and right so that only the used portion of the screen in the center will show. hile not actually affecting the displayed image (the television image in the 4-by-3 aspect ratio will be the same with or without masking), masking the screen adds a degree of sophistication and aesthetic appeal. asking is also a term used when filming a movie or television show when the director wants only a portion of the scene to show up. In such an instance, the camera itself may be masked or partially covered to block out parts of a scene similar to how parts of the screen are masked in a projection television masking scheme.