Danswing paper: A novel visual information presentation technique which gives motion illusions to static printed materials on luminance-changing background

Research background

NTT conducts scientific studies on human information processing. In the course of the study, we treat perceptual illusions as research subject. Recently, NTT have tried to implement perceptual illusions into the real world and proposed a novel and rich visual information technique that gives illusory impressions to objects in the real world.

So far, NTT has proposed several visual presentation methods that based on light projection techniques such as "Hengento" and "Ukuzo". These techniques are useful to give vivid motion impressions to printed materials by presenting image information that can cause visual illusions to users. On the other hand, these techniques requires video projectors. The installation/implementation of the video projectors sometimes became restrictions for actual usages of these techniques in the real world setting. There were room to develop visual presentation techniques that do not use video projectors.

This study focused on a striking visual illusion that has been reported by Gregory and Heard (1983) ^1. They reported that a static object apparently moves based on the interaction between the luminance of the object's contour and background luminance change. On the other hand, no studies have ever proposed a technique to use the illusion in the real world setting. In addition, the reported illusion was related to only horizontal movements, and therefore it was necessary to develop techniques to give richer impressions of illusory motion to a static object.

^1.Gregory, R. L. & Heard, P. F. (1983). Quarterly Journal of Experimental Psychology (1983) 35A, 217-237

Achievement of this study

We proposed a design technique to give illusory motion impressions to real objects by employing the visual illusion reported by Gregory and Heard (1983). In the technique, users create a printed material that has specific patterns of black and white contours, and put it on a luminance-varying display. Users perceive drastic impressions of motion for the static printed materials that undergo our technique. By manipulating the shape and width of the contours, it is possible to add various motion impressions to a static object such as rotation, expansion/contraction, and deformation.

Future plan

NTT tries to propose novel and interesting information presentation techniques that lead to perceptual rich appearances of real objects.

NTT developed this technique without a collaboration with other research institutions.

Some points of this technique

(1) How to create black and white contours that can create illusory motion impressions

This technique takes advantages of a layer structure in image processing as shown in Figure 1. First, prepare an image to which users want to give motion impression (Figure 1 explains how to give motion impressions to a gray heart image). Second, create white and black heart images that have an identical shape to the gray one. Third, slightly rotate the white heart in a clockwise direction while slightly rotate the black heart in an anticlockwise direction. Fourth, synthesize these three heart images so that the gray heart comes in most front of all. Consequently, a gray heart image with black and white contours is obtained. The black and white contours can produce visual motion illusions. Fifth, print out the gray heart, and cut the background out. When the cut heart object is put on a display with temporal luminance modulation, users perceive illusory motion of the object.

(2) Specified conditions for robust presentation of the illusion

Based on a psychophysical experiment to examine the critical width of black and white contours that could produce visual illusion, we proposed that the contour width less than 0.25 degree of visual angle was desirable to robustly give motion impressions to a static printed material.

(3) Use case of this technique with electric paper

By combining this technique with an electric paper that can dynamically control reflectance, it is possible to give motion impressions to objects outside a building. An electric paper is a reflection-based display and can present images with high luminance contrast even under strong ambient light (a normal light-emission-based display occasionally fails to display high luminance/contrast images under such environment). The combination of the technique with electric paper will lead to successful presentation of advertisements and/or signage outside a building.