Search

Integral imaging has been considered as the most applicable technology of true 3D display in the near future. In this paper, we propose the method to achieve full parallax and large-screen integral imaging display based on mini LED. Compared to the existing integral imaging systems based on the LED, the proposed method can present both horizontal and vertical parallaxes. We explore the optical parameter matching method between mini LED display unit and lenslet unit and design three different shapes of lenslet arrays. The imaging performance of lenslet arrays of circular-shape, square-shape, and hexagonal-shape is analyzed. The method of window interception is proposed to generate elemental images for the lenslet arrays with different apertures and arranging structures. The experimental results show that the true 3D display with full parallax and screen scalability has been realized using the proposed method and the display effect of lenslet array with hexagonal-shape is the best according to the evaluation of both subjective and objective merits.

In order to improve depth extraction accuracy, a method using moving array lenslet technique (MALT) in pickup stage is proposed, which can decrease the depth interval caused by pixelation. In this method, the lenslet array is moved along the horizontal and vertical directions simultaneously for N times in a pitch to get N sets of elemental images. Computational integral imaging reconstruction method for MALT is taken to obtain the slice images of the 3D scene, and the sum modulus (SMD) blur metric is taken on these slice images to achieve the depth information of the 3D scene. Simulation and optical experiments are carried out to verify the feasibility of this method.

In this paper, we present a resolution-enhanced computational integral imaging reconstruction method by using boundary folding mirrors. In the proposed method, to improve the resolution of the computationally reconstructed 3D images, the direct and reflected light information of the 3D objects through a lenslet array with boundary folding mirrors is recorded as a combined elemental image array. Then, the ray tracing method is employed to synthesize the regular elemental image array by using a combined elemental image array. From the experimental results, we can verify that the proposed method can improve the visual quality of the computationally reconstructed 3D images.

In this paper, we present a three-dimensional (3-D) automatic target recognition system based on optical integral imaging reconstruction. In integral imaging, elemental images of the reference and target 3-D objects are obtained through a lenslet array or a camera array. Then, reconstructed 3-D images at various reconstruction depths can be optically generated on the output plane by back-projecting these elemental images onto a display panel. 3-D automatic target recognition can be implemented using computational integral imaging reconstruction and digital nonlinear correlation filters. However, these methods require non-trivial computation time for reconstruction and recognition. Instead, we implement 3-D automatic target recognition using optical cross-correlation between the reconstructed 3-D reference and target images at the same reconstruction depth. Our method depends on an all-optical structure to realize a real-time 3-D automatic target recognition system. In addition, we use a nonlinear correlation filter to improve recognition performance. To prove our proposed method, we carry out the optical experiments and report recognition results.

In this paper, we propose a new high-resolution depth estimation algorithm in integral imaging which can obtain threedimensional (3D) images by using lenslet array. In conventional studies, a stereo-matching is used for depth estimation. However, it is not the best solution for integral imaging since the 3D images are usually low-resolution images. Therefore, we propose a pixel blink rate based algorithm using pixel of the elemental images rearrangement technique (PERT) in integral imaging. Through our optical experiment, the depth resolution by our technique is dramatically improved compared with a conventional method.

In this paper, we propose a new computational reconstruction technique of integral imaging for depth resolution enhancement by using integer-valued and non-uniform shifting pixels. In a general integral imaging system, we can record and visualize (or display) 3D object using lenslet array. In previous studies, many reconstruction techniques such as computational volumetric reconstruction and pixel of elemental images rearrangement technique (PERT) have been reported. However, a conventional computational volumetric reconstruction technique has low visual quality and depth resolution because low resolution elemental images and uniformly distributed shifting pixels are used for reconstruction. On the other hand, our proposed method uses non-uniformly distributed shifting pixels for reconstruction instead of uniformly distributed shifting pixels in conventional computational volumetric reconstruction. Thus, the visual quality and depth resolution may be enhanced. Finally, our experimental results show the improvement of depth resolution and visual quality of the reconstructed 3D images.

In this paper, we propose a new fast computational integral imaging reconstruction (CIIR) scheme without the deterioration of the spatial filtering effect by combined use of spatial filtering and rearrangement of elemental image pixels. In the proposed scheme, the elemental image array (EIA) recorded by lenslet array is spatially filtered through the convolution of depth-dependent delta function array for a given depth. Then, the spatially filtered EIA is reconstructed as the 3D slice image using pixels of the elemental image rearrangement technique. Our scheme provides both the fast calculation with the same properties of the conventional CIIR and the improved visual quality of the reconstructed 3D slice image. To verify our scheme, we perform preliminary experiments and compare other techniques.

In this paper, we propose a new computational volumetric reconstruction technique of three-dimensional (3D) integral imaging for depth resolution enhancement by using non-uniform and integer-valued shifting pixels. In a typical integral imaging system, 3D images can be recorded and visualized using a lenslet array. In previous studies, many computational reconstruction techniques such as computational volumetric reconstruction and pixel of elemental images rearrangement technique (PERT) have been reported. However, a computational volumetric reconstruction technique has low visual quality and depth resolution because low-resolution elemental images and uniformly distributed shifting pixels are used for reconstruction. Although PERT can enhanced the visual quality of the 3D images, the size of the reconstructed 3D images is different from the original scene. On the other hand, our proposed method uses non-uniformly distributed shifting pixels for reconstruction instead of uniformly distributed shifting pixels. Therefore, the visual quality and depth resolution may be enhanced. Finally, our experimental results show the improvement of depth resolution and visual quality of the reconstructed 3D images.

Purpose – Full parallax integral 3D display is one of the promising future displays that provide different perspectives according to viewing direction. In this paper, the authors review the recent integral 3D display and image processing techniques for improving the performance, such as viewing resolution, viewing angle, etc.Design/methodology/approach – Firstly, to improve the viewing resolution of 3D images in the integral imaging display with lenslet array, the authors present 3D integral imaging display with focused mode using the time-multiplexed display. Compared with the original integral imaging with focused mode, the authors use the electrical masks and the corresponding elemental image set. In this system, the authors can generate the resolution-improved 3D images with the n×n pixels from each lenslet by using n×n time-multiplexed display. Secondly, a new image processing technique related to the elemental image generation for 3D scenes is presented. With the information provided by the Kinect device, the array of elemental images for an integral imaging display is generated.Findings – From their first work, the authors improved the resolution of 3D images by using the time-multiplexing technique through the demonstration of the 24 inch integral imaging system. Authors’ method can be applied to a practical application. Next, the proposed method with the Kinect device can gain a competitive advantage over other methods for the capture of integral images of big 3D scenes. The main advantage of fusing the Kinect and the integral imaging concepts is the acquisition speed, and the small amount of handled data.Originality / Value – In this paper, the authors review their recent methods related to integral 3D display and image processing technique.Research type – general review.

This paper describes a novel depth extraction method for 3D objects using the windowing technique in computational integral imaging with a lenslet array. The proposed method includes pickup through a lenslet array with a snapshot, introduction of slice image pairs obtained from the windowing technique, and extraction of depth information using block matching between the slice image pairs. Also, this paper presents a theory of how the windowing technique works for depth extraction and an analysis of how it enables us to have a depth image from low-resolution elemental images. A preliminary optical experiment indicates that the proposed method provides a substantial improvement on the depth extraction technique in computational integral imaging with a lenslet array.

In this paper, we propose a novel approach to enhance the recognition performance of a far and partially occluded three-dimensional (3-D) target in computational curving-effective integral imaging (CEII) by using the direct pixel-mapping (DPM) method. With this scheme, the elemental image array (EIA) originally picked up from a far and partially occluded 3-D target can be converted into a new EIA just like the one virtually picked up from a target located close to the lenslet array. Due to this characteristic of DPM, resolution and quality of the reconstructed target image can be highly enhanced, which results in a significant improvement of recognition performance of a far 3-D object. Experimental results reveal that image quality of the reconstructed target image and object recognition performance of the proposed system have been improved by 1.75 dB and 4.56% on the average in PSNR (peak-to-peak signal-to-noise ratio) and NCC (normalized correlation coefficient), respectively, compared to the conventional system.

In this paper, we propose a curved projection integral imaging system to improve the horizontal and vertical viewing angles. The proposed system can be easily implemented by additional use of a large-aperture convex lens in conventional projection integral imaging. To obtain the simultaneous display of 3D images through real and virtual image fields, we propose a computer-generated pickup method based on ray optics and elemental images, which are synthesized for the proposed system. To show the feasibility of the proposed system, preliminary experiments are carried out. Experimental results indicate that our system improves the viewing angle and displays 3D images simultaneously in real and virtual image fields.

In this paper, we present a method to implement computational three dimensional (3D) integral imaging (II). This method is based on Pixels of the Elemental Image Rearrangement Technique (PERT). In our proposed method for computational reconstruction of II, the reconstructed 3D image is obtained by using the entire elemental images which are captured from the lenslet array. Instead of averaging the elemental images, our proposed method rearranges pixels of each elemental image. Therefore, the reconstructed 3D image has the same number of pixels as the entire elemental images' pixels. To verify this computational reconstruction method, we have implemented optical experiments.

Computational integral imaging(CII) has the advantage of generating the volumetric information of the 3D scene without optical devices. However, the reconstruction process of CII requires increasingly larger sizes of reconstructed images and then the computational cost increases as the distance between the lenslet array and the reconstructed output plane increases. In this paper, to overcome this problem, we propose a novel CII method using a depth conversion technique. The proposed method can move a far 3D object near the lenslet array and reduce the computational cost dramatically. To show the usefulness of the proposed method, we carry out the preliminary experiment and its results are presented.

In this letter, we propose a novel computational integral imaging reconstruction technique based on a lenslet array model. The proposed technique provides improvement of viewing images by extracting multiple pixels from elemental images according to ray tracing based on the lenslet array model. To show the feasibility of the proposed technique, we analyze it according to ray optics and present the experimental results.

We propose a computational reconstruction technique in large-depth integral imaging where the elemental images have information of three-dimensional objects through real and virtual image fields. In the proposed technique, we reconstruct full volume information from the elemental images through both real and virtual image fields. Here, we use uniform mappings of elemental images with the size of the lenslet regardless of the distance between the lenslet array and reconstruction image plane. To show the feasibility of the proposed reconstruction technique, we perform preliminary experiments and present experimental results.

In this paper, a modified large-depth integral imaging (LDII) scheme with parallax controllability using a two-dimensional (2-D) lenslet array is proposed. The proposed scheme can generate unidirectional-parallax elemental images by modifying 2-D elemental images picked up by the conventional LDII. The unidirectional-parallax elemental images are obtained by magnifying the single horizontal (or vertical) pixel line of each elemental image to the vertical (or horizontal) size of a lenslet to display three-dimensional (3-D) images. When the unidirectional-parallax elemental image is used, we can obtain reduction in the amount of ray information of elemental images by sacrificing the parallax along the orthogonal direction. Another advantage of the proposed scheme is that we can switch between the full-parallax mode and the unidirectional-parallax mode. That is, it is possible to display 3-D images using either 2-D elemental images for full parallax 3-D or unidirectional-parallax elemental images selectively because of the optical structure using a two-dimensional lenslet array. The feasibility of our scheme is experimentally demonstrated.

We propose a method and present applications of this method that converts a diffraction pattern into an elemental image set in order to display them on an integral imaging based display setup. We generate elemental images based on diffraction calculations as an alternative to commonly used ray tracing methods. Ray tracing methods do not accommodate the interference and diffraction phenomena. Our proposed method enables us to obtain elemental images from a holographic recording of a 3D object/scene. The diffraction pattern can be either numerically generated data or digitally acquired optical data. The method shows the connection between a hologram (diffraction pattern) and an elemental image set of the same 3D object. We showed three examples, one of which is the digitally captured optical diffraction tomography data of an epithelium cell. We obtained optical reconstructions with our integral imaging display setup where we used a digital lenslet array. We also obtained numerical reconstructions, again by using the diffraction calculations, for comparison. The digital and optical reconstruction results are in good agreement. (C) 2012 Optical Society of America

Cataloged from PDF version of article. We present a digital integral imaging system. A Fresnel lenslet array pattern is written on a phase-only LCoS spatial light modulator device (SLM) to replace the regular analog lenslet array in a conventional integral imaging system. We theoretically analyze the capture part of the proposed system based on Fresnel wave propagation formulation. Because of pixelation and quantization of the lenslet array pattern, higher diffraction orders and multiple focal points emerge. Because of the multiple focal planes introduced by the discrete lenslets, multiple image planes are observed. The use of discrete lenslet arrays also causes some other artifacts on the recorded elemental images. The results reduce to those available in the literature when the effects introduced by the discrete nature of the lenslets are omitted. We performed simulations of the capture part. It is possible to obtain the elemental images with an acceptable visual quality. We also constructed an optical integral imaging system with both capture and display parts using the proposed discrete Fresnel lenslet array written on a SLM. Optical results when self-luminous objects, such as an LED array, are used indicate that the proposed system yields satisfactory results. © 2011 Optical Society of America

In this paper, a novel three-dimensional (3-D) integral imaging system to simultaneously improve the depth-of-focus (DOF) and the resolution of the reconstructed object images by using the non-uniform lenslet array and the intermediate-view reconstruction technique (IVRT) is proposed. That is, by using the non-uniform lenslets, DOF-enhanced integral images of 3-D objects can be picked up, and then by applying the IVRT to these picked-up integral images, resolution as well as DOF-enhanced object images can be reconstructed. To show the feasibility of the proposed system, experiments with test objects are performed and the results are discussed.

In this paper, a magnification display of three-dimensional images in one-dimensional integral imaging system using lenslet array is proposed. To show the feasibility of proposed system, some experiments are carried out and results are presented.

In this paper, we present the characteristics of integral imaging systems with large depth when using plane illumination and diffusing illumination. For each system, we perform ray analysis based on ray optics. To check visual quality through optical experiments, we use an average image of observed images pickuped at various positions within large depth. Experimental results show that the use of diffusing illumination can improve visual quality of reconstruction 3-D images in large depth integral imaging system.

A novel optical encryption method is proposed in this paper to achieve 3-D image encryption. This proposed encryption algorithm combines the use of computational integral imaging (CII) and linear-complemented maximum-length cellular automata (LC-MLCA) to encrypt a 3D image. In the encryption process, the 2-D elemental image array (EIA) recorded by light rays of the 3-D image are mapped inversely through the lenslet array according the ray tracing theory. Next, the 2-D EIA is encrypted by LC-MLCA algorithm. When decrypting the encrypted image, the 2-D EIA is recovered by the LC-MLCA. Using the computational integral imaging reconstruction (CIIR) technique and a 3-D object is subsequently reconstructed on the output plane from the 2-D recovered EIA. Because the 2-D EIA is composed of a number of elemental images having their own perspectives of a 3-D image, even if the encrypted image is seriously harmed, the 3-D image can be successfully reconstructed only with partial data. To verify the usefulness of the proposed algorithm, we perform computational experiments and present the experimental results for various attacks. The experiments demonstrate that the proposed encryption method is valid and exhibits strong robustness and security.