Yoshio Ookuma

Psychophysical estimation of 3D virtual depth of united, synthesized and mixed type stereograms by means of simultaneous observation

Recently, many types of computer-generated stereograms (CGSs), i.e. various works of art produced by using computer are published for hobby and entertainment. It is said that activation of brain, improvement of visual eye sight, decrease of mental stress, effect of healing, etc. are expected when properly appreciating a kind of CGS as the stereoscopic view. There is a lot of information on the internet web site concerning all aspects of stereogram history, science, social organization, various types of stereograms, and free software for generating CGS. Generally, the CGS is classified into nine types: (1) stereo pair type, (2) anaglyph type, (3) repeated pattern type, (4) embedded type, (5) random dot stereogram (RDS), (6) single image stereogram (SIS), (7) united stereogram, (8) synthesized stereogram, and (9) mixed or multiple type stereogram. Each stereogram has advantages and disadvantages when viewing directly the stereogram with two eyes by training with a little patience. In this study, the characteristics of united, synthesized and mixed type stereograms, the role and composition of depth map image (DMI) called hidden image or picture, and the effect of irregular shift of texture pattern image called wall paper are discussed from the viewpoint of psychophysical estimation of 3D virtual depth and visual quality of virtual image by means of simultaneous observation in the case of the parallel viewing method.

Psychophysical effect of retouched and modified digital stereograms for binocular vision on depth perception

A stereogram differs from the 3D picture often called stereo pair in appearance. There is no need of special viewer or glasses for stereopsis when viewing the sterograms. It is possible to intuitively carry out the intuitive estimation of depth perception by simultaneously viewing two pairs of stereograms which are arranged the upper and lower sides, or the right and left sides. In this study, modified digital color stereograms are directly viewed on the LCD screen or hard copy images by means of (a) crossing view method or (b) parallel view method. The apparent depth perception of stereograms can be effectively demonstrated by an adjustment of the viewing distance between the eye position of an observer and the plane of a stereogram rather than by altering the size and its arrangement of basic patterns which construct the plane images for steropsis. The visual effect of depth perception in the modified digital stereogram using sharpening filtering operation are discussed in connection with the modified various stereograms under the specified conditions: the number of pixel resolution and color bit levels.

Achromatic or quasi-color Fourier transform hologram and optical diffraction images

A binary computer generated hologram (CGH) and a Fourier Transform hologram (FTH) with gray level/quasi-colors are similar to all appearance in the structure of hologram cell. However, they are wholly different in display techniques by the use of gray level or quasi-colors. It is possible to directly take a picture of reduced FTH, i.e., a kind of positive and negative transparency, displayed on a standard color LCD/CRT using a negative film with high contrast.