Light-emitting diode (LED) technology is presently targeted to displace traditional light sources in backlighted signage.
The literature shows that brightness and contrast are perhaps the two most important elements of a sign that determine its
attention-getting capabilities and its legibility. Presently, there are no luminance standards for signage, and the practice
of developing brighter signs to compete with signs in adjacent businesses is becoming more commonplace. Sign
luminances in such cases may far exceed what people usually need for identifying and reading a sign. Furthermore, the
practice of higher sign luminance than needed has many negative consequences, including higher energy use and light
To move toward development of a recommendation for lighted signage, several laboratory human factors evaluations
were conducted. A scale model of a storefront was used to present human subjects with a typical red channel-letter sign
at luminances ranging from 8 cd/m2 to 1512 cd/m2 under four background luminances typical of nighttime outdoor and
daytime inside-mall conditions (1, 100, 300, 1000 cd/m2), from three scaled viewing distances (30, 60, 340 ft), and either
in isolation or adjacent to two similar signs. Subjects rated the brightness, acceptability, and ease of reading of the test
sign for each combination of sign and background luminances and scaled viewing distances.