Jong-Young Hong

Recent issues on integral imaging and its applications

In this review paper, the recent progress of 3D applications using integral imaging is introduced. Thanks to the progress of the flat panel displays, the quality of the 3D displays has also improved, resulting in the opening of more applications of the 3D display. The previous studies on integral imaging emphasized the improvement of the viewing quality of the integral imaging system, but the emergence of new technologies requires more than the replacement of the current 2D displays. New applications of the integral imaging method, such as displays with augmented reality, 3D information capturing, real-time processing, the projection-type method, and the integral floating method, and their recent research trends, are introduced.

Depth-expression characteristics of multi-projection 3D display systems [invited].

A multi-projection display consists of multiple projection units. Because of the large amount of data, a multi-projection system shows large, high-quality images. According to the projection geometry and the optical configuration, multi-projection systems show different viewing characteristics for generated three-dimensional images. In this paper, we analyzed the various projection geometries of multi-projection systems, and explained the different depth-expression characteristics for each individual projection geometry. We also demonstrated the depth-expression characteristic of an experimental multi-projection system.

Compact three-dimensional head-mounted display system with Savart plate.

We propose three-dimensional (3D) head-mounted display (HMD) providing multi-focal and wearable functions by using polarization-dependent optical path switching in Savart plate. The multi-focal function is implemented as micro display with high pixel density of 1666 pixels per inches is optically duplicated in longitudinal direction according to the polarization state. The combination of micro display, fast switching polarization rotator and Savart plate retains small form factor suitable for wearable function. The optical aberrations of duplicated panels are investigated by ray tracing according to both wavelength and polarization state. Astigmatism and lateral chromatic aberration of extraordinary wave are compensated by modification of the Savart plate and sub-pixel shifting method, respectively. To verify the feasibility of the proposed system, a prototype of the HMD module for monocular eye is implemented. The module has the compact size of 40 mm by 90 mm by 40 mm and the weight of 131 g with wearable function. The micro display and polarization rotator are synchronized in real-time as 30 Hz and two focal planes are formed at 640 and 900 mm away from eye box, respectively. In experiments, the prototype also provides augmented reality function by combining the optically duplicated panels with a beam splitter. The multi-focal function of the optically duplicated panels without astigmatism and color dispersion compensation is verified. When light field optimization for two additive layers is performed, perspective images are observed, and the integration of real world scene and high quality 3D images is confirmed.

Crosstalk-Reduced Dual-Mode Mobile 3D Display

We propose a novel crosstalk-reduced mobile 3D display system providing high quality 3D images both in portrait mode and landscape mode. We analyze a conventional commercial mobile 3D display system with simulations and experiments. Then we propose a crosstalk-reduced mobile 3D display system. We design a micro lens array film and propose a mapping algorithm for the system. To reduce crosstalk, we adopt the mobile phone with a diamond pentile display panel. We build a demonstration with a parallax barrier film and diamond pentile display. This newly implemented system provides 3D images with a similar quality in both portrait mode and landscape mode. The crosstalk of implemented system is 8.3% in portrait mode and 9.2% in landscape mode.

See-through multi-projection three-dimensional display using transparent anisotropic diffuser

We propose a see-through multi-projection three-dimensional (3D) display using a transparent anisotropic diffuser. By immersing a metal-coated anisotropic diffuser into index matching oil which has the same refractive index of anisotropic diffuser, a transparent anisotropic diffuser is implemented. The reflectance of the transparent anisotropic diffuser is analyzed with the transfer matrix. Two multi-projection methods are proposed based on reflection type integral imaging and multi-view method. Especially, the reflection type multi-view-based system is realized with a curved anisotropic diffuser. High resolution see-through 3D display can be realized with the proposed methods. They can be used in various applications with the two multi-projection methods. In order to show the augmented reality features, real objects and virtual 3D images are presented at the same time in the experimental setup.

Real-mode depth-fused display with viewer tracking.

A real-mode depth-fused display is proposed by employing an integral imaging method in the depth-fused display system with viewer tracking. By giving depth-fusing effect between a transparent display and a floated planar two-dimensional image generated by the real-mode integral imaging method, a three-dimensional image is generated in front of the display plane unlike conventional depth-fused displays. The viewing angle of the system is expanded with a viewer tracking method. In addition, dynamic vertical and horizontal motion parallax can be given according to the tracked position of the viewer. As the depth-fusing effect is not dependent on the viewing distance, accommodation cue and motion parallax are provided for a wide range of viewing position. We demonstrate the feasibility of our proposed method by experimental system.

See-through optical combiner for augmented reality head-mounted display: index-matched anisotropic crystal lens

A novel see-through optical device to combine the real world and the virtual image is proposed which is called an index-matched anisotropic crystal lens (IMACL). The convex lens made of anisotropic crystal is enveloped with the isotropic material having same refractive index with the extraordinary refractive index of the anisotropic crystal. This optical device functions as the transparent glass or lens according to the polarization state of the incident light. With the novel optical property, IMACL can be utilized in the see-through near eye display, or head-mounted display for augmented reality. The optical property of the proposed optical device is analyzed and aberration by the anisotropic property of the index-matched anisotropic crystal lens is described with the simulation. The concept of the head-mounted display using IMACL is introduced and various optical performances such as field of view, form factor and transmittance are analyzed. The prototype is implemented to verify the proposed system and experimental results show the mixture between the virtual image and real world scene.

Compact multi-projection 3D display system with light-guide projection.

We propose a compact multi-projection based multi-view 3D display system using an optical light-guide, and perform an analysis of the characteristics of the image for distortion compensation via an optically equivalent model of the light-guide. The projected image traveling through the light-guide experiences multiple total internal reflections at the interface. As a result, the projection distance in the horizontal direction is effectively reduced to the thickness of the light-guide, and the projection part of the multi-projection based multi-view 3D display system is minimized. In addition, we deduce an equivalent model of such a light-guide to simplify the analysis of the image distortion in the light-guide. From the equivalent model, the focus of the image is adjusted, and pre-distorted images for each projection unit are calculated by two-step image rectification in air and the material. The distortion-compensated view images are represented on the exit surface of the light-guide when the light-guide is located in the intended position. Viewing zones are generated by combining the light-guide projection system, a vertical diffuser, and a Fresnel lens. The feasibility of the proposed method is experimentally verified and a ten-view 3D display system with a minimized structure is implemented.

See-through multi-view 3D display with parallax barrier

In this paper, we propose the see-through parallax barrier type multi-view display with transparent liquid crystal display (LCD). The transparency of LCD is realized by detaching the backlight unit. The number of views in the proposed system is minimized to enlarge the aperture size of parallax barrier, which determines the transparency. For compensating the shortness of the number of viewpoints, eye tracking method is applied to provide large number of views and vertical parallax. Through experiments, a prototype of see-through autostereoscopic 3D display with parallax barrier is implemented, and the system parameters of transmittance, crosstalk, and barrier structure perception are analyzed.

Calibration Method for the Panel-type Multi-view Display

School of Electrical Engineering, Seoul National University, Gwanak-ro 1, Gwanak-gu, Seoul 151-744, Korea(Received April 24, 2015 : revised August 17, 2015 : accepted September 1, 2015)We propose a novel calibration method which can be applied to all kinds of panel-type multi-view displays. We analyze how the angular, the axial, and the lateral misalignment affects the 3D image quality in a panel-type multi-view display. We demonstrate the ray optics simulation with a 3-view slanted parallax barrier system using pentile display for the quantitative calculation. Based on the analysis, we propose a new alignment pattern for all kinds of panel-type multi-view displays. The proposed pattern is sensitive to all of the angular, the axial, and the lateral misalignments. The high spatial frequency images and on and off alignment in the proposed pattern help observers to calibrate the system easily. We theoretically show the generality of the proposed alignment pattern and verify the pattern with image simulations and experiments.Keywords : Multi-view display, 3D displayOCIS codes : (100.6890) Three-dimensional image processing; (110.2990) Image formation theory