214 Ergonomics in the Automotive Design Process
It is important to note that the contrast ratios of displays are affected considerably by the ambient
light reected and scattered inside the display optics or lenses. Thus, the ergonomics engineer must
be careful when determining the contrast ratio for inputting in the program. The author found out
that many speedometer graphic elements, which had measured values of contrast ratio above 8 in
the studio or laboratory environment, had much lower contrast ratios of about 1.5–3 when measured
outdoors in the daytime with a photometer. The reduction in contrast due to sunlight falling on the
display surface and scattering inside the display elements is also a notable problem with many new
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