To view displays, we look at an object and then perceive some kind of information. Using displays is a visual method of communication: the transfer of information to be perceived visually by the viewer (Figure 4.7).

Selecting the ideal display is therefore based on the requirements for visual com­munication. What kinds of information have to be transferred to the viewers? There is a huge difference in the requirements between a display in the airport directing pas­sengers to the right gate and the display used in the control room, viewing such data and information as spreadsheets, graphs, production details, overviews, SCADA, and CCTV. This leads us to the question, what are the fundamentals of viewing? Fundamentals of Viewing

The first fundamental to consider is the amount of information in a single image (Figure 4.8).

The basic requirement for how much information can be viewed at any one time is that the information should be ‘perceivable’. When the information is textual, this becomes a matter of the size of the typeface in relation to the viewing distance. With more information and a smaller font used in the image, the viewing distance will need to be shorter (that is, closer to the screen).

Resolution is another way of describing the amount of information in a display. The more information needed, the higher the resolution required.





FIGURE 4.6 (a) An image in 3200 Kelvin. (b) The same image in 5600 Kelvin. (See colour