This paper proposes a novel system enables aerial light-field television system. Our aerial light-field TV system consists of a light-field camera, a light-field display, and an aerial imaging optics. Our light-field camera is composed of an imaging lens and a micro-lens array on a high-resolution image sensor. Our light-field display is composed of a lens array, a slightly diffuser plate, and a high-resolution flat panel display. The diffuser plate is used to eliminate noticeable fringes due to the black matrix on the flat panel display. Our aerial imaging optics is composed of a projection lens, a beam splitter, and a retro-reflector. The principle is called AIRR (aerial imaging by retro-reflection). In this work, AIRR forms the aerial image of the projection lens. That is, the light coming out of the projection lens transmits the beam splitter and impinges the retro-reflector. The retro-reflected light reflects on the beam splitter and converges to the aerial image position of the projection lens. When the viewer’s eyes are in front of the aerial image position, the viewer can recognize the reconstructed aerial light-field image. In the conventional light-field camera and display system, image conversion in each elemental image was needed in order to show the true 3D depth. Because imaging optics forms an inverted image in each elemental image. On the contrary, our aerial light-field TV system requires no image conversion because the aerial imaging optics converts the depth. Thus, it is possible to reconstruct the light-field image in the air in real time.
The paradigm theorem of light field optics is different from that of conventional imaging optics. The conditions for rays in a 3D space are reconstructed from the light field data shown on a 2D high definition flat display through the lens array. A light field display consists of a flat display and lens array attached on its screen. The light field display can be regarded as a transformation system for the light field data. Further, the light field data can be considered as 3D space information in another domain. It contains information of rays in a space, and a point light source in space is expressed as information of many rays that go through the point light source. A point light source in space represents a set of many point light sources, and each ray that composes a point light source should be described in the light field data. Therefore, the light field flat display requires a much higher resolution as compared to that required by a conventional imaging device, on which a point light source can be expressed by a single pixel. In this study, we developed various light field displays using high definition flat displays, introduced the theorem of light field display, and reported the examples of our experimental light field displays.
Light-field optics is used in light-field cameras to alter the focus condition of an image after it is obtained. This unique function implies that information captured with a light-field camera is not a “picture”; rather, it is a real object image. Thus, a two-dimensional (2-D) image of any focus condition can be generated from the acquired data. An explanation is provided on how a light-field camera records or encodes a three-dimensional (3-D) scene onto a 2-D plane as light-field data, and how the data are decoded back into a 3-D image with a light-field display. Other unique applications based on light-field optics are discussed. Unlike conventional optical systems, light-field optics does not require optical conjugation between the display plane and image plane. Thus, light-field optics can provide an effective means of advancement for conventional optical instruments. To demonstrate the potential applications of light-field optics, we developed a light-field camera and display.
When an image shown on an 8K display is projected onto the entire hemisphere, the size of a single pixel is almost equal to 1’, which is same as human visual acuity. This indicates that the resolution of an 8K display is beyond the visual ability of humans, in most cases. A display can show not only an image, but also coded information on its screen. When this ultra-high-definition display is used as a light-field display that consists of a high-definition display and lens array plate, its redundancy of resolution is used for depth information of 3D objects, and a volume 3D image can be reconstructed near the screen. We fabricate a 3D light-field display using a 4K cellular phone and obtain a good image quality. An 8K display is more suitable for a light-field display that generates 3D images of higher resolutions, although the reproduced depth is limited. Herein, I report our light-field display utilizing an ultra-high-definition flat display.
Proc. SPIE. 9867, Three-Dimensional Imaging, Visualization, and Display 2016
KEYWORDS: Image visualization, 3D acquisition, 3D image reconstruction, 3D image reconstruction, Computational imaging, Cameras, Sensors, Image processing, Image resolution, Data acquisition, LCDs, Data processing, Sensing systems, 3D displays, 3D displays, 3D image processing
Light field optics and its applications become rather popular in these days. With light field optics or light field thesis, real 3D space can be described in 2D plane as 4D data, which we call as light field data. This process can be divided in two procedures. First, real3D scene is optically reduced with imaging lens. Second, this optically reduced 3D image is encoded into light field data. In later procedure we can say that 3D information is encoded onto a plane as 2D data by lens array plate. This transformation is reversible and acquired light field data can be decoded again into 3D image with the arrayed lens plate. "Refocusing" (focusing image on your favorite point after taking a picture), light-field camera's most popular function, is some kind of sectioning process from encoded 3D data (light field data) to 2D image.
In this paper at first I show our actual light field camera and our 3D display using acquired and computer-simulated light field data, on which real 3D image is reconstructed. In second I explain our data processing method whose arithmetic operation is performed not in Fourier domain but in real domain. Then our 3D display system is characterized by a few features; reconstructed image is of finer resolutions than density of arrayed lenses and it is not necessary to adjust lens array plate to flat display on which light field data is displayed.
Conference Committee Involvement (5)
Ultra-High-Definition Imaging Systems V
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