Abstract
The visibility and the legibility of the traffic sign are influenced by illumination and contrast of the sign. Aiming at the establishment of the optical design method of the sign, we investigate legibility by the combination of illumination and contrast. First the complexity of the Chinese character was evaluated by the spatial frequencies. Next, experimental sign was examined as imitating the real traffic sign. The visibility and the legibility of the sign was investigated by displaying the character classified by the derived evaluation method. As the result, a preferable combination of illumination and contrast was shown for all age subjects.
