Why is intensity measured if sterance is a better measure of the effect light has on the observer?
While sterance is a good measure of the effect light has on the observer, it unfortunately cannot be measured in a cost effective manner. Also, it is only reliable for diffused parts. It is not effective for direct view displays. The difficulty with direct view displays is trying to determine the light emitting area. For example, take 0.15″, 0.2″ and 0.27″ SAN displays. Let’s try using the area of the LED die. This assumption implies that the three SANs should appear to have the same brightness. However, our eyes tell us that the 0. 15″ is brighter than the 0.2″ which is brighter than the 0.27″. Next, suppose we use the character area. Thus, a ‘ #‘ displayed on 0.1511 will calculate to be brighter than a ‘#’ displayed on a 0.2″, which will calculate to be brighter than a’#’ displayed on a 0.27″. In this case, the sterance is equal to the sum of the intensities of all the on LEDs divided by the character size area. However, what happens if we compare a ‘ #’ to a ‘.’ on the same characte
