TABLE OF CONTENTS The use of small screens as a tool for displaying dynamic information is becoming ubiquitous. Displays range from very simple screens as seen on clocks, microwaves, alarm systems, and so on, to highly capable graphical displays as seen on mobile phones, medical devices, handheld gaming devices, and personal digital assistants (PDAs). The number of products sold with small screens is staggering. Mobile phone sales, just one category of small-screen products, were estimated at 825 million units in 2005 (Gohring, 2006) and have over 2.6 billion subscribers worldwide (Nystedt, 2006). In comparison, personal computer (PC) sales were estimated at 208.6 million units in 2005 (Williams & Cowley, 2006).
Small-screen design primarily makes use of the visual system. Questions in small-screen design often center on how small data elements can be displayed so that they are properly seen or recognized. To gain a deeper understanding of the answers to this question, a brief background of light, eye anatomy, and the sensitivity and acuity of the eye are discussed.
Light is generally described by its wavelength and intensity. The subjective or psychological correlate to wavelength is color (more accurately known as hue). Thus, the color that people see is their perception of the light's wavelength. Wavelength is measured in nanometers (nm). The subjective or psychological correlate to intensity is brightness. Brightness is the impression produced by the intensity of light striking the eye and visual system.
People do not normally look...
