Integral 3D imaging is getting much attention as one of the viable candidates for natural 3D display. Compared with other stereoscopic techniques, it provides more freedom of viewing and sense of naturalness with reduced eye fatigue. Recently several approaches on the projection integral imaging have been issued because of its merits for large size implementation. However, the use of a concave or convex lens array can cause problems of high cost and spherical aberration. To overcome these problems, we propose a novel scheme using multi-facet flat mirrors and demonstrate its feasibility. Instead of spherical mirrors in a flat surface, multi-facet mirrors which contacts with the tangential line of a curved surface function like elemental mirror component. Lights reflected from different facet of each mirrors give different viewing perspectives. By using electronic capturing and display devices, the proposed method makes it possible to record and reconstruct 3D scene in real-time. In the experiment, only horizontal parallax is provided because one-dimensional surface can be made more easily. But extension for two-dimensional or computer generation of elemental images can be also done. Some detailed discussions on the design parameters will be shown in the presentation.
Depth-enhanced integral three-dimensional (3D) imaging using different optical path lengths and polarization selective mirror pair is proposed. In this approach, the enhancement of image depth is achieved by repositioning two types of elemental image planes, thus effectively two central depth planes are obtained. The system makes use of two-arm-structure that has different optical path lengths and polarization selective mirrors. The primary advantage of our proposed method is that we can observe 3D images that maintain some level of viewing resolution with large depth difference without any mechanical moving part. We experimentally demonstrated our proposal by reconstructing real and virtual images with the depth difference of 140 mm successfully.
KEYWORDS: Polarization, Imaging arrays, Image enhancement, Switching, Integral imaging, Stereoscopy, 3D displays, Camera shutters, 3D image processing, Image processing
The integral 3D imaging provides full motion parallax unlike other conventional stereoscopy-based techniques. To make most of this advantage, a 3D system that has a wide view along full direction is required. In this paper, we propose and demonstrate a method to enhance the viewing angle in integral imaging along both horizontal and vertical direction. Proposed system consists of two sub systems that have properly designed polarizing masks. The viewing angle enhancement along full direction is achieved by elemental lens switching that combines time and spatial multiplexing of different elemental image arrays. Some experimental results and the method to avoid a cross-talk effect are shown and discussed.
Integral imaging (or called integral photography) is an attractive three-dimensional display method because of its many advantages over other three-dimensional display methods. However, the thickness of the displayed three-dimensional image which can be expressed is limited by various optical parameters of the system and is relatively small. In this paper, we propose a method to increase the thickness of the displayed three-dimensional image without severe resolution degradation by adopting a birefringent material and a dynamic polarizer. We explain the principle of the proposed method and verify it experimentally.
Integral imaging has been received much interest due to its various advantages. However, the narrow viewing angle is one of the bottlenecks of this technique. Basically, the viewing angle is limited because the displayed area of elemental images is confined. In addition, the interference of neighboring elemental lenses causes the integrated image overlapping. Recently the viewing-angle-enhanced scheme with lens switching has been proposed. In that scheme, a mechanical moving part with fast speed to obtain a natural after-image was required. In this paper, we propose and demonstrate a novel scheme of integral imaging using a mask with two devices to enhance the viewing angle. This is implemented by two identical systems that consist of a lens array and a display panel. The images from the two sets of devices are combined with a beam splitter. A mask that has alternately repeated on/off patterns in an array form is attached to each lens array and the area of on/off in two masks are opposite (interleaved). The integrated images in each system are combined spatially and the viewing area is doubled. Thus, it can be stated that spatial multiplexed images instead of the time-multiplexed images contribute to enhance the viewing angle of integral imaging without any mechanical movement.
Recently with the development of pickup and display devices, real-time integral photography or integral imaging has been an attractive method over other techniques for displaying three-dimensional images. However, previous methods basically belong to the transmission-type display. In this paper, a reflection-type integral imaging is studied and some experimental results are shown to prove its feasibility. This can be implemented by adopting a concave mirror array instead of a convex lens array. A concave mirror array in the reflection-type functions like a lens array in the conventional transmission-type. Thus, the 3D image is integrated by the rays that reflect from a mirror array. We could obtain autostereoscopic images with full parallax. In addition, if we combine the reflection-type system with another conventional transmission-type system, the feeling of depth can be more enhanced. A schematic of a concave mirror array on a curved surface is also proposed and discussed. The curved surface concentrates the rays to a small-sized display panel such as a beam projector. We expect this new form of integral imaging will contribute to realize a practical 3-D display system.
Stereo matching is a method to obtain the depth information from images and is one of the most important issues in the field of machine vision. Contrary to the conventional stereo matching algorithms that involve two or more wellcalibrated cameras, the depth extraction scheme using a lens array is compact and requires no calibration since only one camera is involved in its setup. In this paper, we present a novel depth extraction algorithm using a lens array. The proposed method rearranges horizontal positions of the pixels from the collection of the elemental images to form subimages horizontally leaving the vertical positions of the pixels unchanged. On this rearranged images, we apply a correlation-based multiple-baseline stereo algorithm in properly modified form. The main feature of the proposed method is its ability of exact depth extraction from the extremely periodically patterned object scenes. Additionally, the proposed method enlarges the available depth range due to the reverse dependency of the disparity on the depth between the elemental image and the sub-image. We prove our idea by applying our method on the object scene generated by a computer. The simulation result shows the proposed method extracts precise depth information from the scene of the object with a periodic texture pattern.
The integral photography which is also called integral imaging (II) is an attractive autostereoscopic display method for its many advantages such as continuous viewpoints and no need for any viewing aids. In spite of many advantages of II, the narrow viewing angle has been a bottleneck of it. In this paper, we propose a method to enhance the viewing angle of II by opening and shutting the elemental lenses sequentially. We prove our idea by using a mask that has patterns of on/off. It has vertical or horizontal apertures in an array form, whose interval matches that of the lenses in the II. Both theoretical discussion and experimental result are presented.
Integral photography, which provides continuous viewpoints and does not require any use of special glasses, is one of the most attractive methods for autostereoscopic display. To overcome the difficulties of pickup process and the pseudoscopic problem, a CGIP(Computer-Generated Integral Photography) method is desirable. In the CGIP scheme, the elemental images of imaginary objects are generated using computer instead of using pickup process. This easiness for generating elemental images makes the system compact and cost effective. For a wide viewing angle system, the f-number (the ratio of focal length to lens diameter) of the elemental lens should be small. However, the lens aberration is the penalty of the lens array with small f-number. Unlike the system using a conventional lens array, aberration occurs little in the case of adopting a well-designed Fresnel lens array which has small f-number. Fresnel lens array contributes to widen the viewing angle in the CGIP system. In addition, to increase the image depth range, dynamic integral photography is also proposed. The gap between a lens array and a display panel changes dynamically. Synchronized elemental image array for real and virtual mode is integrated in front of or behind the lens array. Therefore, observers get enhanced feeling of depth. In this way, autostereoscopic 3-D images with wide viewing angle and increased image depth can be obtained. The method can be usefully applicable to three-dimensional imaging.
Stereovision is an effective method in acquiring three-dimensional data from a real scene and forms a very active field of research. The conventional stereovision system usually consists of two or more cameras and therefore the system is bulky and has some problems like a camera calibration. In this paper, we propose a new scheme to acquire three-dimensional data from one camera and a lens array which consists of many elemental lenses. An algorithm that is appropriate for the proposed scheme is discussed and experimental results are presented.
In this paper, we propose a CGIP (Computer-Generated Integral Photography) method and verify its feasibility. In CGIP, the elemental images of imaginary objects are computer-generated instead of using pickup process. Since this system is composed of only one lens array and conventional display devices, it is compact and cost effective. The animated image can also be presented by the time-varying elemental images. As a result, autostereoscopic images with full color and full parallax were observed in real time. Moreover, this method can be applied to a quasi-3D display system. If each camera picks a scene which is a part of total view and elemental images are generated so that each scene has different depth, real objects captured by ordinary cameras can be displayed in quasi-3D. In addition, since it is easy to change the shape or size of elemental images in this scheme, we can observe the effect of several viewing parameters. This helps us to analyze the basic IP system. We perform an experiment with different lens arrays and compare the results. The lateral and depth resolution of the integrated image is limited by some factors such as the image position, object thickness, the lens width, and the pixel size of display panel.
The wavelength selectivity of the hologram using the reference beams with random phase codes and multiple wavelengths is calculated and compared with experimental results. If the angle between signal and reference beams goes to 180 degrees, the effect of random phase code does not significantly affect the wavelength selectivity. Cross-talk noise analysis is Fourier holographic memory using random phase codes and multiple wavelengths is performed, and the signal-to-noise ratio is shown to depend on the angle between signal and reference beams as well as the wavelength difference.
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