We propose an optical viewer based on the integral method. The viewer composed of two GRIN lens arrays and a diffuser in between can form observable three-dimensional images of objects. The length of the elemental GRIN lenses that constitute the arrays is three quarters of the cycle of the meandering ray path on the input side and one quarter of the cycle on the output side. By substituting the diffuser with an image intensifier as an optical amplifier, we were able to observe 3-D images of objects placed in a dark space without the use of a camera or display equipment. The primitive experimental results proved the viewer produces three-dimensional images that can be observed. We also describe the visual resolution characteristics.

In this paper, we address coherent optical imaging techniques for real time automated three-dimensional (3D) sensing, visualization and recognition of dynamic biological microorganisms. Real time sensing and 3D reconstruction of the dynamic biological microorganisms is performed using the single-exposure on-line (SEOL) digital holographic microscopy. A coherent 3D microscope-based interferometer is used to record digital holograms of dynamic micro biological events. Complex amplitude 3D images of the biological microorganisms are computationally reconstructed at different depths by Fresnel propagation algorithm. Statistical segmentation algorithms are applied to identify regions of interest for further processing. Statistical pattern recognition approaches are addressed to identify and recognize the microorganisms. Experimental results with biological microorganisms are presented to illustrate detection, segmentation, and identification of biological events.

Integral imaging systems are imaging devices that provide 3D images of 3D objects. When integral imaging systems work in their standard configuration they provide reconstructed images that are pseudoscopic, distorted and with very poor depth of field. Along the last four years our group has been working in the search of solutions for these drawbacks. Here we present hybrid technique which by means of optical method and digital processing allows the reconstruction of orthoscopic, undistorted, long-focal-depth integral images. Simulated and real imaging experiments are presented to support our proposal.

In this paper, we propose an integral imaging with variable image planes using PDLC (polymer-dispersed liquid crystal) films. Parallel layered PDLC films and a projector are adopted as a display system and enable to vary the location of image plane. We can control the transparency of PDLC films electrically and make each film diffuse the projected light successively with different depth from lens array. The explanation of the proposed system is provided and the experimental results are also presented.

A mobile phone (Hand Phone) is designed to display stereo images taken from a camera attached to it. Software of processing a stereo image pair to be displayed on the display panel of the phone is developed and a detachable viewing zone forming optics is installed for the stereoscopic image generation without moires. Since the phone is operating only in the palm of the phone's owner, special cares needed in photographing the image pair are described.

A three-dimensional (3D) imaging system which consists of an equipment for stereo vision capturing and optical wavefront recontruction is developed. In the system, after acquisition of stereo images, depth maps are calculated by means of an area-based stereo matching algorithm. Hologram pattern is generated from the obtained depth maps with digital signal processing and displayed on a spatial light modulator. A three-dimensional image is reconstructed by illuminating plane wave of coherent light to the modulator. The attractve feature of the imaging system is to contstruct a holographic display without an optical interferometer for hologram recording. We fabricate a prototype of a stereo vision equipment and capture a target object. To obtain the depth map, we apply various methods of area-based stereo maching. The experimental results showed that a sum of absolute difference method provides desired depth maps. We calcuate an in-line hologram pattern with electronic signal processing. In the numerical reconstruction, 3D objects are reconstructed successfully. These results have shown usefulness of the proposed system.

This paper describes recent advances in the field of autostereoscopic display development and introduces an appropriate integration of a novel user interaction technology. Beside technical aspects of the developed autostereoscopic display technology, the paper includes topics of our video-based interaction technique and introduces promising applications of autostereoscopic single user displays. Based on results of the European ATTEST project, the Fraunhofer Institute for Telecommunications (HHI) has developed the Free2C 3D display technology, which provides free positioning of a single viewer. The optics of the Free2C displays is designed such that extremely low crosstalk, excellent color reproduction and high brightness are achieved. Simple and intuitive interaction is a requirement for multi-modal 3D displays. For this reason, a novel technology has been integrated into the control console that can recognize a persons' hand and its gestures. Displayed 3D objects floating in front of the screen can be rotated by simple gestures and virtual buttons can be pressed by pointing at them (virtual 3D touch screen). Several applications are currently used by customers and have been presented at trade shows, exhibitions and showrooms. Feasible applications are based on computer generated content, live video created by stereoscopic cameras and films stored on hard disk. Immersive media presentations are one promising application for attractive stereoscopic representations. The Free2C Kiosk and the 3D Media Center combine a high-resolution autostereoscopic 3D display with a video-based hand-gesture recognition device for direct manipulation of virtual 3D objects floating in front of the screen.

Two approaches in designing autostereoscopic displays capable of providing collaborative viewing of real time 3D scenery will be presented and discussed. Both techniques provide multiscopic "look around" capabilities and are applicable for situation rooms or mobile command centers. In particular, we discuss a prospective use of these displays for interactive visualization of detailed three-dimensional models of urban areas, and the specific demands associated with managing and rendering large volumes of highly detailed information. Latest advances in scanning, survey and registration in urban areas have provided a wealth of detailed three-dimensional data and imagery. Recent events have shown a severe need and demand for systems capable in a high-level 3D visualization upon homeland security posed by terrorist actions and natural disasters within urban areas, as well as for military operations in urban terrain (MOUT). The capacity to visualize sightlines, airflow, flooding, and traffic in real time 3D within dense urban environments is increasingly critical for military and civilian authorities, as well as urban planners and city managers. Development of a high-quality 3D imaging systems is critical also for such areas as medical data imaging, gaming industry, mechanical design and rapid prototyping.

We have developed prototypes of flatbed-type autostereoscopic display systems using one-dimensional integral imaging method. The integral imaging system reproduces light beams similar of those produced by a real object. Our display architecture is suitable for flatbed configurations because it has a large margin for viewing distance and angle and has continuous motion parallax. We have applied our technology to 15.4-inch displays. We realized horizontal resolution of 480 with 12 parallaxes due to adoption of mosaic pixel arrangement of the display panel. It allows viewers to see high quality autostereoscopic images. Viewing the display from angle allows the viewer to experience 3-D images that stand out several centimeters from the surface of the display. Mixed reality of virtual 3-D objects and real objects are also realized on a flatbed display. In seeking reproduction of natural 3-D images on the flatbed display, we developed proprietary software. The fast playback of the CG movie contents and real-time interaction are realized with the aid of a graphics card. Realization of the safety 3-D images to the human beings is very important. Therefore, we have measured the effects on the visual function and evaluated the biological effects. For example, the accommodation and convergence were measured at the same time. The various biological effects are also measured before and after the task of watching 3-D images. We have found that our displays show better results than those to a conventional stereoscopic display. The new technology opens up new areas of application for 3-D displays, including arcade games, e-learning, simulations of buildings and landscapes, and even 3-D menus in restaurants.

Digital holography is an inherently three-dimensional (3D) technique for the capture of real-world objects. Many existing 3D imaging and processing techniques are based on the explicit combination of several 2D perspectives (or light stripes, etc.) through digital image processing. The advantage of recording a hologram is that multiple 2D perspectives can be optically combined in parallel, and in a constant number of steps independent of the hologram size. Although holography and its capabilities have been known for many decades, it is only very recently that digital holography has been practically investigated due to the recent development of megapixel digital sensors with sufficient spatial resolution and dynamic range. The applications of digital holography could include 3D television, virtual reality, and medical imaging. If these applications are realized, compression standards will have to be defined. We outline the techniques that have been proposed to date for the compression of digital hologram data and show that they are comparable to the performance of what in communication theory is known as optimal signal quantization. We adapt the optimal signal quantization technique to complex-valued 2D signals. The technique relies on knowledge of the histograms of real and imaginary values in the digital holograms. Our digital holograms of 3D objects are captured using phase-shift interferometry. We complete the compression procedure by applying lossless techniques to the quantized holographic pixels.

A HMD type multi-focus 3D display system is developed and experiment about satisfaction of eye accommodation is tested. Four LEDs(Light Emitting Diode) and a DMD are used to generate four parallax images at single eye and any mechanical part is not included in this system. The multi-focus means the ability of monocular depth cue to various depth levels. By achieving multi-focus function, we developed a 3D display system for only one eye, which can satisfy the accommodation to displayed virtual objects within defined depths. Therefore this proposed 3D display system has a possibility to solve the problem that the 3-dimensional image display system using only binocular disparity can induce the eye fatigue because of the mismatch between the accommodation of each eye and the convergence of two eyes. The accommodation of one eye is tested and a proof of the satisfaction of the accommodation is given as a result by using the proposed 3D display system. We could achieve a result that focus adjustment is possible at 4 step depths in sequence within 2m depth for only one eye.

This paper proposes a scalable coding scheme for interactive streaming of dynamic light fields, in which a region of interest (ROI) approach is applied for multi-view image sets. In our method, the image segments that are essential for synthesizing the view requested by a remote user are included in an ROI, which is compressed and transmitted with high priority. Since the data for the desired view are transmitted with the data for its neighboring views as the ROI, the user can render high quality novel views around the desired viewpoint before the arrival of the next frame data. Thus our method can compensate the movement of the remote user even if the network has high latency. Since the user can arbitrarily choose the movable range of the viewpoint by changing the size and weight ratio of the ROI, we call this functionality view-dependent scalability. Using a modified JPEG2000 codec, we evaluated the view-dependent scalability of our scheme by measuring the quality of synthesized views against the distance from the originally desired viewpoint.

Depth image based rendering (DIBR) is a method for converting 2D material to stereoscopic 3D. With DIBR, information contained in a gray-level (luminance intensity) depth map is used to shift pixels in the 2D image to generate a new image as if it were captured from a new viewpoint. The larger the shift (binocular parallax), the larger is the perceived depth of the generated stereoscopic pair. However, a major problem with DIBR is that the shifted pixels now occupy new positions and leave areas that they originally occupied "empty." These disoccluded regions have to be filled properly, otherwise they can degrade image quality. In this study we investigated different methods for filling these disoccluded regions: (a) Filling regions with a constant color, (b) filling regions with horizontal linear interpolation of values on the hole border, (c) solving the Laplace equation on the hole boundary and propagate the values inside the region, (d) horizontal extrapolation with depth information taken into account, (e) variational inpainting with depth information taken into account, and (f) preprocessing of the depth map to prevent disoccluded regions from appearing. The methods differed in the time required for computing and filling, and the appearance of the filled-in regions. We assessed the subjective image quality outcome for several stereoscopic test images in which the left-eye view was the source and the right-eye view was a rendered view, in line with suggestions in the literature for the asymmetrical coding of stereoscopic images.

We propose a new imaging optics called the Transmissive Mirror Device (TMD). It consists of numerous micromirrors placed perpendicular to the surface of a flat, thin metal plate. The micro-mirror array is implemented by the inner walls of minute square holes, which are densely pitted on the device. The basic mode of operation is based on two reflections by a pair of adjacent mutually perpendicular mirrors, i.e., a dihedral corner reflector. Although the principal of operation is based on reflection by mirrors, the device is also transmissive and deflects light. Since this imaging system forms a real image at a plane symmetric point, the depth of the 3D image is inverted. Its optical defects are low optical transmittance and stray light caused by non-reflected light and that reflected once. We manufactured the device experimentally with nano-precision machining technology and also evaluated it.

In this paper, we present a system to reconstruct perspective view of a partially occluded object by using computational integral imaging. The system is analyzed to extract information of off-centered views from a elemental images set. To obtain unobstructed images with high resolution, low focus error, and large depth of focus, synthetic aperture integral imaging utilizing a digital camera has been adopted.

We overview a class of optical imaging systems utilizing volume holograms as imaging elements. The three-dimensional (3D) nature of volume holograms as optical elements enables the realization of very general shift-invariant impulse responses and dispersion relationships. We present experimental results and computational approaches towards the analysis and optimization of 3D optical systems. The results indicate promising applications in profilometry of reflective objects and slice-wise hyper-spectral imaging of fluorescent objects without or with minimal scanning.

Integral floating imaging is a 3D display method which is a combination of integral imaging and floating display. It is a promising technique of 3D display because it possesses full parallax, continuous viewpoints and can produce large feel of depth. In this paper, we explain the principle of the integral floating 3D display system and analyze its viewing characteristics, such as viewing angle, viewing window and the expressible depth range. We analyze these characteristics by using geometrical optics based on the analyses on the integral imaging. Experimental results which verify the analyses are provided.

We developed a new virtual reality (VR) system that enables direct interaction between a 3D image and a finger without wearing special 3D glasses and without attaching any marker or detector to the finger. Moreover, it frees the user from visual fatigue. The system consists of a 128-directional 3D display, a PC cluster, and a fingertip detection system. The 128-directional display provides a natural 3D image which does not have the accommodation-vergence conflict and has very smooth motion parallax. It differs from conventional multi-view displays in that it precisely reconstructs rays from a 3D object. It contains 128 LCD panels, and the 128 images displayed on them are projected in different horizontal directions with a horizontal angle pitch of 0.23°. The PC cluster consists of 16 PCs. Each PC generates eight video signals. The fingertip detection system employs a stereo infrared (IR) camera. The 3D position of the fingertip is estimated by triangulation. We also made three application programs. The first one enables the fingertip manipulation of a 3D image in VRML format. The second one is a 3D drawing program that allows users to draw lines in the air. The last one enables the rotation of a 3D image of a 360° directional image by the finger.

There have been reported several researches on gaze tracking techniques using monocular camera or stereo camera. The most popular used gaze estimation techniques are based on PCCR (Pupil Center & Cornea Reflection). These techniques are for gaze tracking for 2D screen or images. In this paper, we address the gaze-based 3D interaction to stereo image for 3D virtual space. To the best of our knowledge, our paper first addresses the 3D gaze interaction techniques to 3D display system. Our research goal is the estimation of both of gaze direction and gaze depth. Until now, the most researches are focused on only gaze direction for the application to 2D display system. It should be noted that both of gaze direction and gaze depth should be estimated for the gaze-based interaction in 3D virtual space. In this paper, we address the gaze-based 3D interaction techniques with glassless stereo display. The estimation of gaze direction and gaze depth from both eyes is a new important research topic for gaze-based 3D interaction. We present our approach for the estimation of gaze direction and gaze depth and show experimentation results.

There have been many researches on multi-view image processing for free viewpoint image generation. However, most of the previous studies focused on the way to generate free viewpoint images with a sense of naturalness considering simplicity of computation and real time processing. One of the merits of the free viewpoint TV is to generate some images that correspond to the user's viewpoint. In this paper, we present a smart remote controller to enjoy a future 3D TV. The proposed controller is smart in that it provides the users with some candidate viewpoints and they are automatically computed based on the theory of human visual attention. The candidate viewpoints are generated from the analysis of an input image by human visual attention model.

The 3D-2D convertibility is essential for the penetration of the 3D display into the current 2D display market and various methods were proposed to realize it. In this paper, a thin size 3D-2D convertible display using a pinhole array on a polarizer is proposed. The thickness of the proposed system can be below one centimeter. Additionally, the use of a pinhole array on a polarizer enhances the light efficiency of the proposed system in the 2D mode by more than ten times of the 3D mode. This is also essential since the 3D mode is an additional function for a 3D-2D convertible system. As a result, the 2D image quality of the proposed system can be compatible with the existing 2D displays for most aspects. The method is proven by experimental results.

We developed a 3D display using an LCD display panel and a grating film for stereoscopic viewing. The display screen is divided in half in order that left and right regions provide the stereoscopic images for left and right eyes. Because both stereoscopic images are not in the same position, it is difficult for the observer to view the 3D image by the stereoviewing. We solved this problem using a polarized LCD panel and a grating film. The optical grating film shifts both left and right images to the same position. As the result, the observer can watch overlapped stereoscopic images for left and right eyes.

In this paper, a new II system that can magnify 3-D reconstructed images by employing an intermediate-view reconstruction technique(IVRT) is proposed, in which the number of the elemental images obtained from one-step pickup process could be computationally increased by use of an IVRT without needs of mechanical movement and long multi-step pickup process. To show the feasibility of the proposed II system, some optical experiments on magnification of 3-D reconstructed images with real 3D objects of "toys" have been carried out and its results are presented.

Until now, many of mobile display manufacturers try to improve the contrast ratio, viewing angle, and backlightluminance for its color fidelity and image quality. However, with the multimedia convergence, various imaging devices have been made smaller and loaded in a mobile phone as independent modules, which brings about the necessity of the color consistency between each module. Especially, with the population and rapid growth of mobile camera, it is important for mobile LCD to reproduce realistically and accurately the object color of a moving-picture transmitted by a mobile camera. Therefore, we developed a real-time color matching system between mobile camera and mobile LCD based on a 16-bit lookup table (LUT) design. As a result, a moving-picture is realistically and accurately reproduced on mobile LCD by applying the proposed lookup table to mobile display.

In this paper, we proposed a new coding technique of digital hologram video using 3D scanning method and video compression technique. The proposed coding consists of capturing a digital hologram to separate into RGB color space components, localization by segmenting the fringe pattern, frequency transform using M×N (segment size) 2D DCT (2 Dimensional Discrete Cosine Transform) for extracting redundancy, 3D scan of segment to form a video sequence, motion compensated temporal filtering (MCTF) and modified video coding which uses H.264/AVC. The compressed digital hologram was reconstructed by both computer program and optic system. The proposed algorithm showed better properties after reconstruction with higher compression ratios than the previous researches.

The 3D projection display system using an LCD projector has superior characteristics, such as having a large screen with wide field of view. However, a conventional system has such demerits as viewing stereoscopic images with special glasses. We describe transmission and reflection 3D displays using a polarizer slit barrier. These 3D displays can avoid the problem of conventional system and thus the observer can view glasses-free 3D images.

Using volumetric computational II reconstruction, we are able to recognize distorted occluded objects with correlation based recognition algorithms. We present experimental results which show recognition of 3D rotated targets in a reconstructed occluded scene. We also show the ability of the proposed technique to recognize distorted occluded 3D non-training targets.