抄録
The accommodation mechanism has been experimentally shown to function as a demodulator in perceiving digital-halftone still images. Stimuli used in the experiments consisted of digital-halftone sine-waves and numerical figures expressed by an error-diffusion method. The accommodative responses were measured with an infrared optometer while the subjects perceived the dot component or the signal component modulated by the dots. The following results were obtained: (1) the accommodation lag changes depending on which component is perceived,and increases more for the signal component perception than the dot component; (2) the accommodation lag when perceiving the signal component increases as the sine-wave's spatial frequency decreases and the figure size enlarges; (3) as long as the viewing distance is over 1 diopter,it does not affect the above results. These results suggest that the change of accommodation lag,which corresponds to the bandwidth of low-pass filters,affects how digital-halftone images are perceived,i.e.,that the accommodation mechanism can also play the role of the demodulator in human vision. Moreover,we clarified that the resting state of accommodation does not affect the accommodative responses to digital-halftone images.
