454 IEEE TRANSACTIONS ON BROADCASTING, VOL. 57, NO. 2, JUNE 2011

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1 454 IEEE TRANSACTIONS ON BROADCASTING, VOL. 57, NO. 2, JUNE 2011 A Directional-View and Sound System Using a Tracking Method Youngmin Kim, Joonku Hahn, Young-Hoon Kim, Jonghyun Kim, Gilbae Park, Sung-Wook Min, and Byoungho Lee, Senior Member, IEEE Abstract The use of a tracking method for developing a directional-view display system with directional sound is described. The proposed system allows an individual to experience directional sound in a multi-view display environment. A projection-type display system is used, because a high definition display and large size display screen can be easily realized. We implemented a tracking system with an infrared camera and infrared light emitting diodes to track the viewers positions. A viewing zone analysis that permits complete separation between neighboring view images to be calculated and experimental results for two observers are presented. Index Terms Geometrical optics, three-dimensional displays, ultrasonic applications. I. INTRODUCTION T HE latest upheavals in the display industry began with a development of high speed liquid crystal (LC) elements and information processing. Aside from information processing speed, higher frame rates are becoming an issue because threedimensional (3D) television has recently become commercialized by some of the major display industries. The first 3D television systems used 120 Hz refresh rates, i.e. 60 Hz for the left and right eye respectively [1]. However display devices that have driving speeds equal to or higher than 120 Hz are required because of the finite response time of liquid crystal components and shutter glasses. Although a higher operation speed is not always better in a display field, there are some basics issues that need to be understood. The 3D display devices that are currently being considered have a 240 Hz or 480 Hz refresh rate, which rapidly alternate between blocking out the left and right eyes. A 72 inch light emitting diode 3D TV embedded in a 480 Hz true motion panel was introduced to the market (Consumer Electronics Show 2010). The refresh rate is still a controversial issue in terms of visual fatigue because there remains an unexplained aspect link between visual fatigue and the 3D display. Manuscript received July 15, 2010; revised March 07, 2011; accepted March 08, Date of publication April 19, 2011; date of current version May 25, This work was supported by the Brain Korea 21 Program (Information Technology of Seoul National University) of the Ministry of Education, Science and Technology of Korea. Y. Kim, Y.-H. Kim, J. Kim, G. Park, and B. Lee are with the School of Electrical Engineering, Seoul National University, Seoul , Korea ( byoungho@snu.ac.kr). J. Hahn is with the School of Electronics Engineering, Kyungpook National University, Buk-gu, Daegu , Korea. S.-W. Min is with the Department of Information Display, Kyung Hee University, Dongdaemoon-Gu, Seoul , Korea. Color versions of one or more of the figures in this paper are available online at Digital Object Identifier /TBC In fact there are many different types of 3D displays, and they can be classified into two categories: stereoscopic displays and autostereoscopic displays [2] [4]. Among them, the stereoscopic display and autostereoscopic display such as the parallax barrier, the lenticular lens method, and the integral imaging method show better performance in terms of resolution and crosstalk when they are equipped with a display panel with the above-mentioned high refresh rate [5], [6]. Holography is known as an ideal 3D display technique, since the object wavefront can be correctly reconstructed. However none of these techniques has reached a satisfactory performance level with sufficient practical value. Directional-view displays, that can manipulate view images to the pre-defined positions from the same display device, have been studied extensively during the past decades. The above mentioned 3D display techniques require either a high definition display device or plural display devices for reconstructing a flawless 3D image [7], [8]. However, high priced display panels are required to provide a high definition display for both ways. Therefore it might be practical to consider the directional-view display before the emergence of a fully fledged 3D display market because the directional-view display does not require the high driving speed of LC. Several companies have introduced triple view LC display (LCD) panels that can process up to three different images simultaneously (International Meeting on Information Display 2007 and Flat Panel Display International 2006), depending on the direction of the observer. Because this kind of system enables the use of a display panel for an advertisement board that engages multiple observers simultaneously, it could lead to a breakthrough prior to the emergence of a 3D display market. Although directional-view display techniques that can provide either 3D images or different 2D images have been studied by many research groups [9], the fundamental importance of the sound system with the 3D display device has not been taken into consideration nor examined to date, although preliminary experiments have been presented [10]. It is generally accepted that humans use at least five senses in recognizing physical phenomenon. Among them, vision and hearing are important perception cues offered by a display device. Curiously, despite inseparable relationships between display devices and sound systems, the reason why 3D display technologies did not consider the accompanying development of 3D sound effects is that only one sound content is needed in a typical 3D display. No matter where the individual observer is, it is necessary for one 3D display content to be equipped with one sound system. In this paper, we report on an investigation dealing with the development of a directional-view display with directional /$ IEEE

2 KIM et al.: DIRECTIONAL-VIEW AND SOUND SYSTEM USING A TRACKING METHOD 455 2D display device and optical elements that are capable of splitting view images. The resolution of 3D images can be expressed as (1) Fig. 1. Directional-view (4-view) display system that employs lenticular lens. sound, which can provide the observer with directional sound in a multi-view display environment. Directional sound based on hypersonic sound technology, which can be focused directly at the listening audience, prompted us to offer separated sounds with different views in a confined space. Therefore individual observers could experience different views with different sounds at their corresponding positions. The main purpose of the proposed system is to gauge the applicability of a directional-view display system with directional sound without crosstalk of neighboring directional-view images and interference between directional speakers. We performed an experiment with two observers and also implemented and tested a tracking system to verify that each observer can experience what they want, regardless of their position. II. DIRECTIONAL-VIEW PROJECTION-TYPE DISPLAY Directional-view display methods such as the parallax barrier, the lenticular lens method, integral imaging, and super multi-view displays have been proposed. Directional-view display methods can provide either 3D images or separated 2D images. The difference among these methods is the angular resolution of elemental images [11]. The elemental images behind optical elements are the sources of 3D images or separated 2D images. They are projected to the viewing zones from the same display device or multiple display devices. In the directional-view display, this is determined by the angular resolution of directional rays from the display device, irrespective of whether the directional-view display provides 3D images or separated 2D images. Fig. 1 shows a directional-view (4-view) display system employing lenticular lenses. The display pixels are arranged behind the lenticular lens, and directional rays from display pixels are divided into four views after passing through the lenticular lenses. Because they have a sparse angular resolution for each view, the system can display directional views at corresponding positions. When the display pixels are substituted by an aggregation of display device modules such as spatial light modulators, and directional-view display is organized in such a manner that more than two different images pass through an eye-pupil, a situation referred to as the super multi-view condition. Another method is to increase the angular resolution for natural 3D images by using a high definition display device. The resolution of 3D images depends on both the resolution of the where and are the horizontal and vertical resolution of an -dimensional display, respectively, and is the number of views. For the display system to have more numbers of views, a better angular resolution is required [12] [14]. However currently available 2D display devices do not provide definition that is sufficiently high to express good quality 3D images; it is not likely that natural 3D images will be developed in the near future. Therefore a directional-view display that can provide different 2D images at corresponding positions can act as a stepping stone between a natural 3D display and a high quality 2D display. In a directional-view display, the resolution problem still remains because it requires a high definition 2D display device having -times better resolution to provide -views. A projection-type display represents a potential candidate when the directional-view display is combined with it. The projection-type display has significant advantages over a flat panel display when it is incorporated into a directional-view display [15], [16]: 1) A high definition display can be implemented using multiple projector units. 2) It is easy to realize large-size display because the display screen is separated from the small display module in the projector unit. 3) The projection-type display is appropriate for a directionalview display based on an autostereoscopic display, such as a parallax barrier or the lenticular lens method. Fundamentally a 3D display based on a projection-type display system is not easy to implement because it is difficult to fabricate large-size uniform lenticular lenses and it is also more difficult to align a lenticular lens and display screen including the projector units. However, in this proposed system, angular resolution, which can influence the production of 3D images or separated 2D images, is relatively low. Although the viewing zone can be different as the alignment process proceeds, it is not so difficult to implement a high definition directional-view display system with a large-size screen. III. VIEWING ZONE ANALYSIS When the view images are synthesized, sequential view image generation can bring about incomplete separation of the view images at the boundary. For example, as shown in Fig. 1, when the perspective goes from -th view to the next -th view, both images can be displayed simultaneously. One pixel or group of pixels has its light directed in one direction, and another group in another direction. This enables the image to be split, which results in incomplete separation. Fig. 2 shows the results of incomplete separation. Although the apple and banana are displayed at the corresponding positions, they are not separated at the boundary of each view position. For complete separation between neighboring view images, we inserted a black matrix pattern between the view images, as shown in Fig. 3. The black stripe patterns generate

3 456 IEEE TRANSACTIONS ON BROADCASTING, VOL. 57, NO. 2, JUNE 2011 case, directional rays from the 1st view image satisfy following equations: (2) Fig. 2. Incomplete separation of a view image at the boundary. (3) Directional rays from the 2nd view image satisfy where is black stripe width. When we call the distance between the individual observer and the lenticular lens the minimum distance for the complete separation of the viewing zone, it can be expressed as (4) (5) Fig. 3. Structure of two-view display system including black striped patterns. (6) where is the number of elemental lenticular lenses and is the distance between two eyes. Fig. 4. Directional-view display designed to satisfy minimum distance for complete separation of viewing zones. another viewing region. However this black striped pattern sacrifices the resolution of the display device. Fig. 4 shows some terms used to describe the coordinates of synthesized view images and the viewing zone when a two-view display system including a black striped pattern is generated. For convenience, we let the top of the first lenticular lens coincide with the zero points (0, 0). To be sure that the synthesized view image is separated clearly, both eyes of the individual observer should be placed within each viewing zone. Let us assume that display plane is placed at the focal position of the lenticular lens. In Fig. 4, because we implement a projection-type directional-view display, the display screen is not fixed. The variable is the alignment variable, is the pixel pitch of view image for the 1st view, is the focal length of the lenticular lens, and is the pitch of the lenticular lens. In this IV. DIRECTIONAL SOUND SYSTEM One of the most overlooked factors in directional-view displays is the sound system. No matter where the individual observer is, it is necessary for one display content to be equipped with one sound system because each display content typically has only one sound content in a 3D display. However, in this proposed system, different sound systems according to the separated display contents are required. It is impossible for a general sound system to give different sound contents to individual viewers in a confined space. Recently the directional speaker system, which permits zones of sound to be created, was proposed [17]. This system is based on hypersonic sound technology which can focus the sound directly at the listening audience, analogous to a directional-view display in the field of optics. The principle of hypersonic sound technology involves: sending two frequencies into a nonlinear medium, such as air, which produces an output containing both of the original signals, the sum of the two frequencies, and the difference between the two frequencies. In this situation, two frequencies belong to ultrasonic sound, while an audible frequency is produced in the area where the two ultrasonic wave fronts cross. The directional speaker is a set of electronic devices that produce a complex waveform containing all of the components required to make different tones and the resulting waveform is projected from an ultrasonic emitter, as shown in Fig. 5. Therefore one directional speaker contains all of the components needed to produce one directional sound in an audible frequency. The sound beam is 90 to 95% directional, while the sound from a conventional sound system is about 60% directional at most. As a result, the directional speaker enables individual observers to be provided with separated sounds when a directional-view display system is used. The directional angle can

4 KIM et al.: DIRECTIONAL-VIEW AND SOUND SYSTEM USING A TRACKING METHOD 457 Fig. 5. Basic block diagram of a directional speaker. also be controllable from 7 to 25 degrees by using a customized control box for the directional speaker. The total harmonic distortion rate of directional sound is less than 1% at 1 khz. Because of the property of ultrasonic sound, interference between different sounds from directional speakers does not occur. Intended sounds in an intersection area which is crossed by two ultrasonic sounds can be heard. V. TRACKING SYSTEM In the proposed system, both the directional-view display and directional sound are fixed regardless of position of the observer. In other words, the directional-view images are projected from a single display device to pre-defined positions and directional sound systems are adjusted for the zones. In this case, the observers should be riveted by the directional view and sound system. However it needs to provide freedom to the observers who wish to see what they want in practice. Therefore a tracking technology can be implemented to provide a directional-view and sound environment in accordance with the arbitrary location of an individual observer if the elemental image can be synthesized while the location of observer changes. To proceed with this process in real-time, technology for rapidly following each observer s movement is required. Tracking technology has been used to recognize a user s position and it can be extended to gestures, finger movements, and face detection in the fields of virtual reality and 3D displays [18]. Recently, a high resolution infrared (IR) camera was implemented to extend the functionality of the remote controller of a video game console. In this paper, we employ wireless IR light emitting diodes (LEDs) and a camera to track where the individual observer is located. Since we consider the directional-view and sound system as a large-size display, analogous to a home theater, as shown in Fig. 6, we conclude that tracking technology using IR LEDs and a camera will be a simple and inexpensive option and would be easily adoptable, as in the case of a remote controller [19]. Another reason for using wireless IR technology is its fast response time and short delay. The accuracy of wireless IR cameras and LEDs is approximately one centimeter and its speed of image processing is about 30 frames per second. We adopted IR LEDs as a marker to recognize individual observers by finding a contour algorithm in OpenCV and the results were used to calculate their positions. IR LEDs were equipped with a normal Fig. 6. Concept of directional-view display system with a directional sound. Fig. 7. Systematic diagram for providing directional-view and sound using an IR tracking method. remote controller to provide a depth cue for the IR camera. We evaluated this for two observers, but the system can be expanded by adding more directional speakers, IR equipment, and view synthesis. Fig. 7 shows a systematic diagram of the proposed system. VI. EXPERIMENTAL RESULTS To experimentally verify that the proposed system shows directional-view with directional sound using tracking technology, we first attempted to synthesize view images for three observers. The view image consists of three different images, and black striped patterns are inserted between the view images to completely separate neighboring views from one another, as discussed in Sec. III. One pixel or group of pixels has its light directed in one direction, and another group in another direction. This can be accomplished by using a lenticular lens. In this situation, the resolution of reconstructed 2D images that are created after passing them through lenticular lenses decreases to one third or less because of black striped patterns. The resolution of a directional-view image is sacrificed by black striped patterns, while it creates a dark viewing zone between the view images. Therefore it guarantees that each view image

5 458 IEEE TRANSACTIONS ON BROADCASTING, VOL. 57, NO. 2, JUNE 2011 Fig. 8. (Up) Three source images and (down) synthesized elemental image. Fig. 11. Experimental setup. TABLE I EXPERIMENTAL PARAMETERS Fig. 9. (Top) Experimental setup and (left, right, and down) results for view separation. Fig. 10. Directional-view image results for different lens pitch of lenticular lens (up: 3 LPI lenticular lens; down: 20 LPI lenticular lens). Fig. 12. Experimental results (movie file captured at 6 s, 12 s, 15 s, and 21 s). is thoroughly separated because the black striped patterns generate another viewing region; therefore the elemental image including black striped patterns allows the 2D images to be separated at the corresponding positions. Fig. 8 shows three different images as a source of 2D images and their synthesized elemental image. We designed an experimental setup for confirming that the view images are well-separated, as shown in Fig. 9. We used a full HD projector (Panasonic PT-AE1000E) and the resolution of the elemental images was found to be We were able to confirm the role of black striped patterns as a

6 KIM et al.: DIRECTIONAL-VIEW AND SOUND SYSTEM USING A TRACKING METHOD 459 Fig. 13. Four examples of tracking results when two observers are at different positions (top left: observer 1-view 1, observer 2-view 3; top right: observer 1-view 2, observer 2-view-3; down left: observer 1-view 1, observer 2-view 2; down right: observer 1-view 3, observer 2-view 1). compensator of screen visibility. The reason why an autostereoscopic display based on projection-type display adopting parallax barrier or a lenticular lens is not commonly used is the small angle of screen visibility. Alignment between the screen and optical elements is a critical issue in projection-type autostereoscopic displays. When a smudgy screen and a low resolution projector are used, image distortion or crosstalk between neighboring views can occur. The insertion of a black striped pattern is a tentative solution for this problem. As shown in Fig. 9, each directional-view image is well-separated at the corresponding positions. The other issue is to determine optimal lens pitch of the lenticular lens. A lenticular lens with too high lenses-per-inch (LPI) cannot fit the screen visibility and a too low LPI lenticular lens cannot express a natural directional-view image. Fig. 10 shows the experimental results when the optimal lens pitch of the lenticular lens is not used. We tested different lenticular lenses (3 LPI, 20 LPI) for a suitable lens pitch of the lenticular lens. As shown in Fig. 10, when 3 LPI lenticular lenses were used, the resolution of the directional view image was relatively low. On the contrary, the quality of the directional view image is better when 20 LPI lenticular lenses are used, while the view images were not well separated because of the small angle of screen visibility and the small pitch of the lenticular lens. Therefore we employed 10 LPI lenticular lenses in the experiment to achieve high resolution and complete separation of the view image. To verify the proposed system for combined directional-view and directional sound for two observers, we used two directional speakers (DigiFi, Sonicast) and synthesized video files. The experimental setup is shown in Fig. 11 and the experimental parameters are listed in Table I. The screen is located 60 cm in front of the high definition projector and the distance between the lenticular lens and the observation plane is 145 cm. The directional angle of the speakers is set as 10, and maximum performance is attained at a distance of roughly 2 3 m from the individual observer. Two types of video files were synthesized; in one jets of water dance to music while the coupling of light produced rainbow colors. The other is a movie file showing some children celebrating the World Cup on the street. We can easily predict that an individual observer could experience the different video files with different sound contents according to their positions, as shown in Fig. 12. Although there is interference between the two directional speakers in some regions due to the intersection of each directional speaker, by calculating the viewing zone of each observer, as discussed in Section III, we find that the individual observer should be located far enough from projected movies on screen. This is another reason for choosing a projection-type directional-view display system for a large-size screen. For tracking configurations, the viewing region was divided into three views for the two observers. Observer 1 was forced to see the bicycle image as the view 1 image source, and observer 2 was forced to see the ocean image as the view 2 image source in Fig. 8 because they had their own IR LED controllers. In the three viewing zones, each observer could see the assigned directional-view image even if they changed their positions. An IR camera was installed at the top of the lenticular lens, and tracking results are updated on the tracking window as shown in Fig. 13. IR LEDs are used to identify each individual observer. VII. CONCLUSION A directional-view display system with directional sound using a tracking method for two observers is described. The directional sound based on hypersonic sound technology could be focused directly at the listening audience; the individual observers were able to experience different views with different sounds at their corresponding positions. The number

7 460 IEEE TRANSACTIONS ON BROADCASTING, VOL. 57, NO. 2, JUNE 2011 of observers can be expandable as additional view images are created and directional speakers are added. We performed experiments for view image separation for three observers and suitable directional speakers for two observers. By adopting a tracking method, the two observers were able to see and hear what they wished, regardless of their positions. A vehicular display such as a split view in luxury sedans can be equipped with the proposed system. When two or more people disagree, it is best to split up the view image. Currently available vehicular displays allow two different observers to view different images from the same display device, while it cannot support individual sound systems. We believe that the proposed system with directional speakers could be employed instead of cumbersome headsets to insulate individual observers. Even though this was the case, directional view image with directional sound can still be provided without the use of tracking technology. Home theaters and digital signage represent other applications of the proposed system. It can be applied to both small screen views and large-size displays. We can imagine that two or more people in a family might wish to see different programs on one display device at the same time. By adopting the proposed system, each family member could watch and hear TV channels or music videos through directional speakers. Because the tracking technology using IR LEDs and camera could be simply installed in a normal remote controller, different individuals would be able to access the desired channel regardless of their position. [13] J.-H. Park, S.-W. Min, S. Jung, and B. Lee, Analysis of viewing parameters for two display methods based on integral photography, Appl. Opt., vol. 40, pp , [14] L.-H. Wang, X.-J. Huang, M. Xi, D.-X. Li, and M. Zhang, An asymmetric edge adaptive filter for depth generation and hole filling in 3DTV, IEEE Trans. Broadcast., vol. 56, no. 3, pp , Sep [15] J.-S. Jang and B. Javidi, Depth and lateral size control of three-dimensional images in projection integral imaging, Opt. Exp., vol. 12, pp , [16] Y. Kim, S.-g. Park, S.-W. Min, and B. Lee, Integral imaging system using a dual-mode technique, Appl. Opt., vol. 48, pp. H71 H76, [17] F. J. Pompei, The use of airborne ultrasonics for generating audible sound beams, J. Audio Eng. Soc, vol. 47, pp , [18] T. Grossman, D. Wigdor, and R. Balakrishnan, Multi-finger gestural interaction with 3D volumetric displays, presented at the Proceedings of the 17th Annual ACM Symposium on User Interface Software and Technology, Santa Fe, CA, Oct , unpublished. [19] G. Park, J.-H. Jung, K. Hong, Y. Kim, Y.-H. Kim, S.-W. Min, and B. Lee, Multi-viewer tracking integral imaging system and its viewing zone analysis, Opt. Exp., vol. 17, pp , Youngmin Kim received the B.S. degree 2005 and the Ph.D. degree in February 2011, respectively, in electrical engineering from Seoul National University, Seoul, Korea. He remains with the institute as a Postdoctoral Researcher. His current research interests focus on the three-dimensional display, image processing including multi-view three-dimensional display, and visual fatigue of human vision related on three-dimensional display. REFERENCES [1] Three-Dimensional Television: Capture, Transmission, Display,H.M. Ozaktas and L. Onural, Eds.. Heidelberg, Germany: Springer, [2] J. R. Moore, N. A. Dodgson, A. R. L. Travis, and S. R. Lang, Timemultiplexed color autostereoscopic display, Proc. SPIE, vol. 2653, pp , [3] M. Halle, Autostereoscopic displays and computer graphics, presented at the Computer Graphics, ACM SIGGRAPH, 1997, unpublished. [4] Y. Kajiki, H. Yoshikawa, and T. Honda, Hologram-like video images by 45-view stereoscopic display, Proc. SPIE, vol. 3012, pp , [5] Y. Kim, J. Kim, J.-M. Kang, J.-H. Jung, H. Choi, and B. Lee, Point light source integral imaging with improved resolution and viewing angle by the use of electrically movable pinhole array, Opt. Exp., vol. 15, pp , [6] Y. Zhang and A. R. L. Travis, DMD-based autostereoscopic display system for 3D interaction, Electron. Lett., vol. 44, pp , [7] J. Hahn, H. Kim, Y. Kim, G. Park, and B. Lee, Wide viewing angle dynamic holographic stereogram with a curved array of spatial light modulators, Opt. Exp., vol. 16, pp , [8] Y. Takaki and N. Nago, Multi-projection of lenticular displays to construct a 256-view super multi-view display, Opt. Exp., vol. 18, pp , [9] W.-H. Kuo, W.-B. Chou, T.-C. Cheng, P.-C. Yeh, Y.-S. Jeng, C.-J. Hu, and W.-M. Huang, 2D/3D dual-image switchable display, presented at the SID Int. Symp. Digest Tech. Papers, 2008, unpublished. [10] J. Hahn, Y. Kim, and B. Lee, Uniform angular resolution integral imaging display with boundary folding mirrors, Appl. Opt., vol. 48, pp , [11] Y. Kim, Y.-H. Kim, J. Kim, J. Hahn, S.-W. Min, and B. Lee, Multiview display system based on autostereoscopic display with directional sound, Proc. SPIE, vol. 7797, pp U U-6, [12] S.-W. Min, J. Kim, and B. Lee, New characteristic equation of threedimensional integral imaging system and its applications, Jpn. J. Appl. Phys., vol. 44, pp. L71 L74, Joonku Hahn received the Ph.D. degree from School of Electrical Engineering, Seoul National University, Korea, in After receiving the degree, he worked as a Postdoctoral Associate in Electrical and Computer Engineering, Duke University, Durham, NC. In March 2011, he joined Kyungpook National University, Korea as a faculty member. When the main idea of the work in this paper was developed, he was with Seoul National University. Young-Hoon Kim is currently in B.S. program of School of Electrical Engineering, Seoul National University, Seoul, Korea. Jonghyun Kim received the B.S. degree from School of Electrical Engineering, Seoul National University, Seoul, Korea, in February Currently, he is in M.S. program of the same university.

8 KIM et al.: DIRECTIONAL-VIEW AND SOUND SYSTEM USING A TRACKING METHOD 461 Gilbae Park received the B.S. degree from the School of Electrical Engineering at the Korea Advanced Institute of Science and Technology, Daejeon, Korea, in He received the M.S. degree from the School of Electrical Engineering, Seoul National University, Korea, in He is currently working towards the Ph.D. degree at the School of Electrical Engineering, Seoul National University. His primary research interest is in the areas of 3-D displays and computer graphics. Sung-Wook Min received the B.S. and M.S. degrees in electrical engineering from Seoul National University, Korea, in 1995 and 1997, respectively. In August 2004, he received the Ph.D. degree from his alma mater. Presently, he is a faculty member in the Department of Information Display, Kyung Hee University, which he joined in He is interested in 3-D imaging and the advanced display system, especially based on the integral imaging technique. Byoungho Lee (M 94 SM 00) received the Ph.D. degree from Department of Electrical Engineering and Computer Science, University of California at Berkeley in Since 1994, he has been with the School of Electrical Engineering, Seoul National University, Korea as a faculty member, where he is a full professor now. He is a fellow of the Optical Society of America (OSA) and a fellow of the SPIE. His research group has published more than 240 international journal papers and presented more than 340 international conference papers including more than 90 invited papers. His research fields are three-dimensional display, diffractive optics, fiber devices and surface plasmon polariton applications. Dr. Lee received the 5th Young Presidential Scientist Award of Korea in 2002 and the Scientist of the Month Award of Korea in September 2009.