Kyu-hwan Choi

Recent Developments in 3-D Imaging Technologies

Three-dimensional (3D) imaging technologies that have been developed recently are reviewed. In recent years, many new progresses in the 3D imaging have been made but most of them provide more practical solutions to comply with the commercialization efforts of the 3D imaging. Based on time-multiplexing, revisiting the stereoscopic imaging methods is one of the solutions to make possible each view image has the full panel resolution. The rapid progresses of high speed LCDs and the initiation of stereoscopic imaging service to mobile phones have made the method possible. The efforts also encouraged more concerns in evaluating 3-D image quality and identifying factors affecting the quality. In this respect, in-depth analysis has been done for the multiview imaging methods, and other forms of multiview 3D image display methods, such as the focused image/pixel array of multiview images are also analyzed.

Arrayed beam steering device for advanced 3D displays

An arrayed beam steering device enables much simplified system architectures for high quality multiview 3D displays by adapting time multiplexing and eye tracking scheme. An array device consisting of microscale liquid prisms is presented, where the prism surface between two immiscible liquids is electrically controlled to steer light beams by the principle of electrowetting. An array prototype with 280×280μm pixels was fabricated and demonstrated of its full optical performances. The maximum tilting angle of each prism was measured to be 22.5° in average, with a tracking resolution of less than 0.04°. In this paper, we report a design and fabrication of eletrowetting based prism array, opto-fluidic simulations, optical characterizations, as well as applications to achieve low fatigue 3D displays.

Development of micro variable optics array

This research is on the development of a micro variable optics array which employs electrowetting as the working principle. The single pixel of the array has four separated electrodes and each of them is controlled independently giving the device multi-degree of freedom. The separated electrodes are fabricated using a thick photoresist and electroplating. Several formulas showing the relation among the radius of curvature, the prism angle, and electrowetting parameters are provided. The prism angles are measured to be ±30° and compared to the calculated values. The measurement of the radius of curvature is also presented showing that the various radiuses of curvature are achievable from concave to convex.

Eye Tracking based Glasses-free 3D Display by Dynamic Light Field Rendering

Glasses-free 3D display is developed using dynamic light field rendering algorithm in which light field information is mapped in real time based on 3D eye position. We implemented 31.5″ and 10.1″ prototypes.

Three-dimensional display optimization with measurable energy model

3D displays have been developed to provide users with a realistic 3D experience. Although various studies have endeavored to establish design principles for 3D displays, a generalized optimized model does not exist in the literature thus far. These circumstances have led to the manufacture of independently qualified 3D products, but expanding these applications remains a challenge. In this paper, we suggest a measurement model and an optimization method for optimized 3D display design. The proposed optimization can be applied to rotatable 3D displays and various pixel structures. Our experimental results based on manufactured displays and simulations confirm the proposed theory of optimization model.

Feasibility of Eye-tracking based Glasses-free 3D Autostereoscopic Display Systems for Medical 3D Images

Medical image diagnosis processes with stereoscopic depth by 3D display have not been developed widely yet and remain understudied Many stereoscopic displays require glasses that are inappropriate for use in clinical diagnosis/explanation/operating processes in hospitals. An eye-tracking based glasses-free three-dimensional autostereoscopic display monitor system has been developed, and its feasibility for medical 3D images was investigated, as a cardiac CT 3D navigator. Our autostereoscopic system uses slit-barrier with BLU, and it is combined with our vision-based eye tracking system to display 3D images. Dynamic light field rendering technique is applied with the 3D coordinates calculated by the eye-tracker, in order to provide a single viewer the best 3D images with less x-talk. To investigate the feasibility of our autostereoscopic system, 3D volume was rendered from 3D coronary CTA images (512 by 512 by 400). One expert reader identified the three main artery structures (LAD, LCX and RCA) in shorter time than existing 2D display. The reader did not report any eye fatigue or discomfort. In conclusion, we proposed a 3D cardiac CT navigator system with a new glasses-free 3D autostereoscopy, which may improve diagnosis accuracy and fasten diagnosis process.

Glasses-free 2D-3D switchable display using an integrated single light guide plate

To commercialize glasses-free 3D display more widely, the display device should also be able to express 2D images without image quality degradation. Moreover, the thickness of display panel including backlight unit (BLU), and the power consumption should not be increased too much, especially for mobile applications. In this paper, we present a 10.1-inch 2D-3D switchable display using an integrated single light guide plate (LGP) without increasing the thickness and power consumption. The integrated single LGP with a wedge shape is composed of prismatic line patterns on its top surface and straight bump patterns on its bottom surface. The prismatic line patterns, which are composed of micro prisms having the light aperture on one side, act as slit apertures of parallax barriers for 3D mode. The linear bump patterns arranged along the vertical direction scatter the light uniformly together with the reflective film disposed under the LGP for 2D mode. LED light sources are arranged as edge-lit in the left and right sides of the LGP for 2D mode, and on the top edge of the LGP with the wider thickness for 3D mode. Display modes can be simply switched by turning on and off the LED light sources, alternatively. Applying the integrated single LGP, we realized a 2D-3D switchable display prototype with a 10.1-inch tablet panel of WQXGA resolution (2,560 × 1,600), and showed the light-field 3D display with 27-ray mapping and 2D display. Consequently, we acquired brightness uniformity over 70% for 2D and 3D modes.