Toyohiko Hatada

Mechanism of color breakup in field-sequential-color projectors

— To investigate color breakup in field-sequential-color projectors, we measured the threshold of color fusion frequency relative to retinal velocity of the moving edge on the color flicker field. The characteristic changed as the velocity approached saccade. The result suggests that the mechanism of color breakup differs according to the velocity of the image on the retina.

Mechanism of Color Breakup on Field‐Sequential Color Projectors

To investigate color breakup on field-sequential color projector, we measured threshold of color fusion frequency to retinal velocity of the moving edge on the color flicker filed. The characteristic changed in the velocity as saccade. The result suggests that the mechanism of color breakup differs by range of retinal velocity.

A method for reproducing apparent continuous depth in a stereoscopic display using “Depth‐Fused 3D” technology

— A new method that can present fine depth increments in a stereoscopic display is proposed. In typical stereoscopic displays, depth can be presented by binocular disparity, but binocular disparity of less than one pixel cannot be displayed because, in general, electronic displays have discrete pixels. We combined binocular disparity and modulation of the edge luminance in DFD (depth-fused 3D) displays. In an experiment, the perceived depth could be continuously changed by modulating the edge luminance only. Therefore, continuous depth can be produced by combining binocular disparity and modulation of edge luminance distribution.

Time series evaluation of visual fatigue and depth sensation using a stereoscopic display

Abstract Conventional stereoscopic (3D) displays using binocular parallax generate unnatural conflicts between convergence and accommodation. These conflicts can affect the observers ability to fuse binocular images and may cause visual fatigue. In this study, time series changes in visual fatigue and depth sensation when viewing stereoscopic images with changing parallax were examined. In particular, the physiological changes, including the subjective symptoms of visual fatigue, when viewing five parallax conditions, were examined. Then a comparative analysis of the 2D and 3D conditions was performed based on the visual function. To obtain data regarding the visual function, the time series changes in the spontaneous‐blinking rate before and during the viewing of 3D images were measured. The time series change results suggest that 2D and 3D images cause significantly different types of visual fatigue over the range of binocular disparity.

Analysis of physiological impact while reading stereoscopic radiographs

A stereoscopic viewing technology is expected to improve diagnostic performance in terms of reading efficiency by adding one more dimension to the conventional 2D images. Although a stereoscopic technology has been applied to many different field including TV, movies and medical applications, physiological fatigue through reading stereoscopic radiographs has been concerned although no established physiological fatigue data have been provided. In this study, we measured the α-amylase concentration in saliva, heart rates and normalized tissue hemoglobin index (nTHI) in blood of frontal area to estimate physiological fatigue through reading both stereoscopic radiographs and the conventional 2D radiographs. In addition, subjective assessments were also performed. As a result, the pupil contraction occurred just after the reading of the stereoscopic images, but the subjective assessments regarding visual fatigue were nearly identical for the reading the conventional 2D and stereoscopic radiographs. The α-amylase concentration and the nTHI continued to decline while examinees read both 2D and stereoscopic images, which reflected the result of subjective assessment that almost half of the examinees reported to feel sleepy after reading. The subjective assessments regarding brain fatigue showed that there were little differences between 2D and stereoscopic reading. In summary, this study shows that the physiological fatigue caused by stereoscopic reading is equivalent to the conventional 2D reading including ocular fatigue and burden imposed on brain.

Polarization effect of the in-vivo cornea

We studied the polarization effect of the normal cornea by using birefringent special samples (PMMA) which produce polarized pattern similar to those of the in vivo cornea. The observation confirmed the change of polarization patterns in vivo cornea as a function of thickness and optical birefringence of the cornea. We posit that the hyperbolic polarized pattern seen in vivo normal cornea is the change of birefringence in the whole cornea is affected by the external oblique direction of stress, which is necessary to maintain a balanced state of the eye globe.

P‐43: Effects of Changing Image Size on Depth Perception Using a Floating 3‐D Display

A floating-image display produces 3-D effects using a lens system that makes an image appear to float in the air. The authors examine the effects on depth perception and asthenopia of viewing a floating image that continuously changes in size. The results of the experiments suggest that viewers perceive the floating image to be moving back and forth as the image size changes despite the fact that the images actual position does not change. Monocular depth cues, especially changes in size, enhanced the 3-D effects of images presented on the floating-image display.

Standard portrait image and image quality assessment: II. Triplet comparison

We have already proposed a standard portrait for the assessment of preferable skin tone. The present report describes a psycho physical experimental method, i.e., simultaneous triplet comparison that has been developed for the assessment of skin tone by using the portrait and that is characterized not only by a scalability, stability and reproducibility of the resulting scale values, but also by a reduce stress on observers. We have confirmed that the present simultaneous triplet comparison has a degree of scalability and stability almost equivalent to that of paired comparison that is most widely used for similar purposes, and that the stress on observers is about half as much as that of paired comparison.