We previously proposed techniques to eliminate repeated three-dimensional (3D) images produced by the light field Mirage, which consists of circularly aligned multiple-slanted light field displays. ...However, we only constructed the lower half of the system to verify the proposed elimination techniques. In this study, we developed an alignment technique for a complete 360-degree display system. The alignment techniques for conventional 360-degree display systems, which use a large number of projectors, greatly depend on electronic calibration, which indispensably causes image quality degradation. We propose a systematic approach for the alignment for the light field Mirage, which causes less image quality degradation by taking advantage of the small number of display devices required for the light field Mirage. The calibration technique for light field displays, the image stitching technique, and the brightness matching technique are consecutively performed, and the generation of 360-degree 3D images is verified.
A frameless hologram display module employing a modified resolution redistribution system is proposed in this paper. The frameless display modules can be aligned two-dimensionally to realize a large ...display screen. The modified resolution redistribution system consists of a one-lens imaging system, a screen lens, and a multiple illumination system. The prototype module was constructed using a spatial light modulator with a resolution of 1,980 x 1,080, and a pixel pitch of 8.0 microm. The horizontal resolution was increased four times and the magnification of the imaging system was 2.88. The horizontal resolution was increased to 7,920 and the horizontal pixel pitch was reduced to 5.8 microm. The screen size of the module was 2.0 inches and the horizontal viewing angle was 6.3 degrees.
A conflict between accommodation and vergence is one possible cause of visual fatigue and discomfort while viewing conventional three‐dimensional displays. Previous studies have proposed the super ...multi‐view (SMV) display technique to solve the vergence–accommodation conflict, in which two or more parallax images enter the pupil of the eye with highly directional rays. We simultaneously measured accommodative, vergence, and pupillary responses to SMV three‐dimensional displays to examine whether they can reduce the conflict. For comparison, responses to two‐view stereo images and real objects were also measured. The results show that the range of the accommodative response was increased by the SMV images compared with the two‐view images. The slope of the accommodation–vergence response function for the SMV images was similar to that for the real objects rather than the two‐view images. We also found that enhancement of the accommodative range by the SMV images is noticeable with binocular viewing, indicating that vergence‐induced accommodation plays an important role in viewing SMV displays. These results suggest that SMV displays induced a more natural accommodative response than did conventional, two‐view stereo displays. As a result, SMV displays reduced the vergence–accommodation conflict.
We demonstrated that super multi‐view displays can ameliorate the vergence‐accommodation conflict while viewing 3D images. Accommodative, vergence, and pupillary responses of the eyes were measured while viewing super multi‐view images, two‐view images, and real objects. The accommodative response to super multi‐view images coordinates with the vergence response, as is the case in viewing real objects.
A hologram calculation technique is proposed in this study using a depth image and light-field information comprising multiple parallax images. The depth image is used to determine the phase ...distribution of the zone plates, and the amplitude distribution is modulated using the light-field information. An object wave of three-dimensional (3D) objects is obtained by adding the light-field modulated zone plates. The proposed technique can generate sharp and shaded 3D images in space. The occlusion effects of 3D images can also be supported by modifying the amplitude modulation scheme. The proposed technique was experimentally verified.
The generation of full-parallax and 360-degree three-dimensional (3D) images on a table screen is proposed. The proposed system comprises a small array of high-speed projectors and a rotating screen. ...Because the screen has a lens function, a large number of viewpoints are generated on a circle when the screen rotates. Thus, 360-degree 3D images having horizontal parallax are generated. Because all projectors are located at different heights from the screen, they generate the viewpoints on a circle at different heights. Therefore, plural viewpoints are aligned in the vertical direction to provide vertical parallax. A prototype display system that employs three high-speed color projectors is constructed.
To realize large-screen three-dimensional (3D) displays, frameless multi-view display modules are arranged two-dimensionally. This paper proposes a multi-view display module in which a multi-view ...flat-panel display is projected onto a screen of the module to provide a frameless screen. The display module consists of a multi-view flat-panel display, an imaging lens, an aperture, a screen lens, and a vertical diffuser. Prototype display modules were constructed having a screen size of 27.3 in., a 3D resolution of 320 × 200, and 144 viewpoints. Four modules were tiled vertically to provide a screen size of 62.4 in. Distortions in the screen imaging and viewpoint generation were corrected.
Background
Currently, no classification system using magnification endoscopy for the diagnosis of superficial Barrett’s esophagus (BE)-related neoplasia has been widely accepted. This nationwide ...multicenter study aimed to validate the diagnostic accuracy and reproducibility of the magnification endoscopy classification system, including the diagnostic flowchart developed by the Japan Esophageal Society—Barrett’s esophagus working group (JES-BE) for superficial Barrett’s esophagus-related neoplasms.
Methods
The JES-BE acquired high-definition magnification narrow-band imaging (HM-NBI) images of non-dysplastic and dysplastic BE from 10 domestic institutions. A total of 186 high-quality HM-NBI images were selected. Thirty images were used for the training phase and 156 for the validation (test) phase. We invited five non-experts and five expert reviewers. In the training phase, the reviewers discussed how to correctly predict the histology based on the JES-BE criteria. In the validation phase, they evaluated whether the criteria accurately predicted the histology results according to the diagnostic flowchart. The validation phase was performed immediately after the training phase and at 6 weeks thereafter.
Results
The sensitivity and specificity for all reviewers were 87% and 97%, respectively. Overall accuracy, positive predictive value, and negative predictive value were 91%, 98%, and 83%, respectively. The overall strength of inter-observer and intra-observer agreements for dysplastic histology prediction was
κ
= 0.77 and
κ
= 0.83, respectively. No significant difference in diagnostic accuracy and reproducibility between experts and non-experts was found.
Conclusion
The JES-BE classification system, including the diagnostic flowchart for predicting dysplastic BE, is acceptable and reliable, regardless of the clinician’s experience level.
A stereo camera unit which enables the three-dimensional (3D) image acquisition using conventional two-dimensional (2D) rigid endoscopes is proposed. It consists of an afocal optical system, a beam ...splitter, and two cameras. The exit pupil of the endoscope, which exists in the proximity of the eyepiece, is optically transferred to a different position. The beam splitter divides the transferred exit pupil into two identical exit pupils, where the entrance pupils of the two cameras are located. The proposed technique provides a low-cost solution for the construction of 3D endoscopes, because conventional 2D endoscopes can be used and the stereo camera unit can be constructed using off the shelf devices. The preliminary experiments were conducted to verify the proposed technique. The evaluation of the resolution, the subjective evaluation, and task efficiency of 3D images are shown.
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