<Li> Viewing angle is the maximum angle at which images on the monitor can be viewed, without excessive degradation to the image . It is measured in degrees horizontally and vertically . </Li> <P> On two - dimensional display devices such as computer monitors the display size or view able image size is the actual amount of screen space that is available to display a picture, video or working space, without obstruction from the case or other aspects of the unit's design . The main measurements for display devices are: width, height, total area and the diagonal . </P> <P> The size of a display is usually by monitor manufacturers given by the diagonal, i.e. the distance between two opposite screen corners . This method of measurement is inherited from the method used for the first generation of CRT television, when picture tubes with circular faces were in common use . Being circular, it was the external diameter of the glass envelope that described their size . Since these circular tubes were used to display rectangular images, the diagonal measurement of the rectangular image was smaller than the diameter of the tube's face (due to the thickness of the glass). This method continued even when cathode ray tubes were manufactured as rounded rectangles; it had the advantage of being a single number specifying the size, and was not confusing when the aspect ratio was universally 4: 3 . </P> <P> With the introduction of flat panel technology, the diagonal measurement became the actual diagonal of the visible display . This meant that an eighteen - inch LCD had a larger visible area than an eighteen - inch cathode ray tube . </P>

What are the small dots of light on a computer monitor called