Yan-Ling Piao

Resolution-enhancement for an orthographic-view image display in an integral imaging microscope system.

Due to the limitations of micro lens arrays and camera sensors, images on display devices through the integral imaging microscope systems have been suffering for a low-resolution. In this paper, a resolution-enhanced orthographic-view image display method for integral imaging microscopy is proposed and demonstrated. Iterative intermediate-view reconstructions are performed based on bilinear interpolation using neighborhood elemental image information, and a graphics processing unit parallel processing algorithm is applied for fast image processing. The proposed method is verified experimentally and the effective results are presented in this paper.

Development of a real-time integral imaging display system based on graphics processing unit parallel processing using a depth camera

Abstract. A depth camera has been used to capture the depth data and color data for real-world objects. As an integral imaging display system is broadly used, the elemental image array for the captured data needs to be generated and displayed on liquid crystal display. We proposed a real-time integral imaging display system using image processing to simplify the optical arrangement and graphics processing unit parallel processing to reduce the time for computation. The proposed system provides elemental images generated at a rate of more than 30 fps with a resolution of 1204×1204  pixels, where the size of each display panel pixel was 0.1245 mm, and an array of 30×30  lenses, where each lens was 5×5  mm.

Advanced 360-Degree Integral-Floating Display Using a Hidden Point Removal Operator and a Hexagonal Lens Array

An enhanced 360-degree integral-floating three-dimensional display system using a hexagonal lens array and a hidden point removal operator is proposed. Only the visible points of the chosen three-dimensional point cloud model are detected by the hidden point removal operator for each rotating step of the anamorphic optics system, and elemental image arrays are generated for the detected visible points from the corresponding viewpoint. Each elemental image of the elemental image array is generated by a hexagonal grid, due to being captured through a hexagonal lens array. The hidden point removal operator eliminates the overlap problem of points in front and behind, and the hexagonal lens array captures the elemental image arrays with more accurate approximation, so in the end the quality of the displayed image is improved. In an experiment, an anamorphic-optics-system-based 360-degree integral-floating display with improved image quality is demonstrated.

Depth-layer weighted prediction method for a full-color polygon-based holographic system with real objects

We propose a full-color polygon-based holographic system for real three-dimensional (3D) objects using a depth-layer weighted prediction method. The proposed system is composed of four main stages: acquisition, preprocessing, hologram generation, and reconstruction. In the preprocessing stage, the point cloud model is separated into red, green, and blue channels with depth-layer weighted prediction. The color component values are characterized based on the depth information of the real object, then color prediction is derived from the measurement data. The computer-generated holograms reconstruct 3D full-color images with a strong sensation of depth resulting from the polygon approach. The feasibility of the proposed method was confirmed by numerical and optical reconstruction.

Viewing-Angle-Enhanced Integral Imaging Display System Using a Time-Multiplexed Two-Directional Sequential Projection Scheme and a DEIGR Algorithm

We propose and demonstrate a viewing-angle-enhanced integral imaging display (VAEIID) system that uses a time-multiplexed, two-directional sequential projection (TTSP) scheme and a directional elemental image generation and resizing (DEIGR) algorithm. The main idea behind the method is sharing the same image screen to display two-directional elemental image (DEI) sets with a time-multiplexed sequential projection scheme. The proposed system consists of three processes: acquisition of depth and color information of a real object using the Microsoft Kinect sensor, generation of two DEI sets considering two different angular perspectives using a DEIGR algorithm, and projection of two sets of DEIs using the TTSP scheme. Due to the two-directional projections, each elemental lens of the lens array collects two-directional illuminations from the two sets of elemental images (EIs) projected in a time-multiplexed sequential manner by using the TTSP scheme; this produces two point light sources (PLSs) at different positions on the focal plane of the lens array. The positions of the PLSs are predefined and are determined in terms of projection angle. In this case, the viewing angle comprises the combination of two diverging ray bundles emerging from the two DEI sets projected from two angular directions. As a result, the viewing angle of the proposed VAEIID system is enhanced by almost twice that of the conventional method.

Holographic Optical Elements and Application

Holographic optical element has a high diffraction efficiency and a narrow-band frequency characteristic, and it has a characteristic that is able to implement several features in a single flat device. It is widely applied in various fields. In this chapter, the principle and characteristics of the holographic optical elements are described in detail, and few typical holographic optical element-based applications, such as head-mounted display, lens array, and solar concentrator, are introduced. Finally, the futuristic research concepts for holographic optical element-based applications and contents are discussed.

Three-dimensional image acquisition and reconstruction system on a mobile device based on computer-generated integral imaging

A mobile three-dimensional image acquisition and reconstruction system using a computer-generated integral imaging technique is proposed. A depth camera connected to the mobile device acquires the color and depth data of a real object simultaneously, and an elemental image array is generated based on the original three-dimensional information for the object, with lens array specifications input into the mobile device. The three-dimensional visualization of the real object is reconstructed on the mobile display through optical or digital reconstruction methods. The proposed system is implemented successfully and the experimental results certify that the system is an effective and interesting method of displaying real three-dimensional content on a mobile device.

Three dimensional projection-type integral imaging display system using directional projection and elemental image resizing method

Three dimensional projection-type integral imaging display system using directional projection and elemental image resizing method is reported in this paper. In directional elemental image generation, directional projection geometry is considered for each pixel in order to directional elemental image projection. In this scheme, the elemental image resizing method is used to prevent elemental image mismatch with the lens pitch due to directional projection. By using directional elemental image projection scheme, viewing zone of reconstructed image can be controlled according to the directional projection angle.

Advanced mobile three-dimensional display based on computer-generated integral imaging

In this paper, we focused on the improvement of reconstructed image quality of the mobile three-dimensional display using the computer-generated integral imaging. The three-dimensional scanning method is applied instead of capturing the depth image in the acquisition step, and much more accurate three-dimensional view information (parallax and depth) can be acquired compared with the previous mobile three-dimensional integral imaging display, and the proposed system can reconstruct clearer three-dimensional visualizations of real-world objects. Here, the three-dimensional scanner acquires the three-dimensional parallax and depth information of the real-world object by the user. Then, the entire acquired data is organized and the three-dimensional the virtual model is generated based on the acquired data, and the EIA is generated from the virtual three-dimensional model. Additionally, in order to enhance the resolution of the elemental image array, an intermediate-view elemental image generation method is applied. Here, five intermediateview elemental images are generated between each four-original neighboring elemental image according to the pixel information, at least, the resolution of the generated elemental image array is enhanced almost four times than original. When the three-dimensional visualizations of real objects are reconstructed from the elemental image array with enhanced resolution, the quality can be improved quite comparing with the previous mobile three-dimensional imaging system. The proposed method is verified by the real experiment.

Fast calculation method for full-color computer-generated hologram of real objects captured by depth camera

A Fast calculation method for full-color computer-generated hologram of real objects is proposed. In this research, the depth and color information of the real scene is acquired by with a depth camera, and a point cloud model is extracted from the 3D information. The method consists of three steps: the first is calculation of multi-layers located inside the point cloud. In the second step, we separate point cloud model into red-green-blue (RGB) channels using depth-layer weighted prediction. In the third step, in order to obtain the CGH, we execute diffraction calculations based on fast Fourier transform (FFT) from the multi-layers to the CGH, which parallel each other. The numerical simulation results confirm that our proposed method is able to improve CGH computational speed.