Inside the Tube: A Look at Video Monitor Technology (page 4)

Horizontal Resolution

A simple method for demonstrating a monochrome monitor's horizontal resolution is to display special images on the screen. First we connect a high-resolution, black-and-white video camera to the monitor. Then we place in front of the camera the photograph of a white picket fence with about 400 skinny pickets and equally skinny black spaces between them. We turn the switch on and look at the monitor's screen. The electron beam traces identical lines composed of regularly spaced black and white dots, and the entire image of the 400-picket fence appears on the screen. If the image is crisp and clear, and the edges of the pickets and the shadows that separate them are sharp and well defined, we can say that the monitor has a resolution of at least 400 lines. A professional resolution chart offers a similar but more accurate method to determine horizontal resolution.

Figure 5 shows a simplified version the monitor's picket-fence image and the corresponding variations of the electron beam's intensity. The steep vertical slopes of the beam-intensity changes. The faster a monochrome monitor is able to vary its electron-beam intensity, the better its horizontal resol…