One-dimensional integral imaging based on parallax barrier

One-dimensional integral imaging (1DII) which only has horizontal disparity is a practical solution of high resolution in the vertical direction, low-cost, easy-viewable three-dimensional (3D) display. A 1DII based on a parallax barrier is proposed in this paper. The 1DII consists of a parallax barrier and a display panel. The operation principle and parameter calculation of the 1DII are described in detail. Two prototypes of the proposed 1DII and conventional 1DII based on a lenticular lens array are developed. The proposed 1DII improves the quality of the 3D image and provides larger viewing angle than that based on a lenticular lens array, and it is simpler and has lower cost than that based on a lenticular lens array.     

Modified smart pixel mapping method for displaying orthoscopic 3D images in integral imaging

In this paper, we propose a modified smart pixel mapping (MSPM) method for displaying orthoscopic three-dimensional (3D) images with a function of depth control in integral imaging system. In the proposed MSPM, the depth-converted elemental image array (EIA) is obtained through the pixel mapping process and the image interpolation technique. The proposed method gives us the depth conversion at distances different from the position of 3D object and provides various types of EIAs using only an original EIA for orthoscopic images. To show the usefulness of the proposed method, we carry out the preliminary experiments and present the experimental results.     

Efficient compression of rearranged time-multiplexed elemental image arrays in MALT-based three-dimensional integral imaging

In this paper, an approach to efficiently compress the time-multiplexed EIAs picked up from the MALT-based integral imaging system is proposed. In this method, the time-multiplexed EIAs are rearranged by collecting the elemental images occupied at the same position in each EIA to enhance the similarity among the elemental images. Then, MPEG-4 is applied to these rearranged elemental images for compression. From the experimental results, it is shown that the average correlation quality (ACQ) value representing a degree of similarity between the elemental images, and the resultant compression efficiency have been enhanced by 11.50% and 9.97%, respectively on the average for three kinds of test scenarios in the proposed method, compared to those of the conventional method. Good experimental results finally confirmed the feasibility of the proposed scheme.     

Optical display of true 3D objects in depth-priority integral imaging using an active sensor

In this paper, we propose a system combining the pickup process using an active sensor and the display process using depth-priority integral imaging (DPII) system to display true three-dimensional (3D) objects within large depth through real and virtual image fields. The active sensor provides depth map and color images of 3D objects. Using captured depth map and original color images, elemental images are computationally synthesized and displayed optically in DPII system. Proposed system provides scaling of 3D scenes for true 3D object. To show the usefulness of proposed system, we carry out the experiment for true 3D objects of three character patterns and present the experimental results.     

Effect of thickness of parallax barrier on viewing angle of one-dimensional integral imaging display

A parameter design of a parallax barrier is one of the most important keys to design a one-dimensional integral imaging (1DII) display using parallax barrier. The relationship between the thickness of the parallax barrier and the viewing angle of the 1DII display is studied, and the maximal value of the thickness is also obtained. When the thickness of the parallax barrier is greater than the maximal value, the viewing angle of the 1DII display is decreased with increasing the thickness of the parallax barrier. A prototype of the 1DII display using parallax barrier is developed, and the experimental results agree well with the theory.     

Orthoscopic integral imaging display by use of the computational method based on lenslet model

In this paper, we propose a computational depth conversion method based on the lenslet model to display the orthoscopic 3D images in 3D integral imaging display. The proposed method permits the synthesis of elemental images for the orthoscopic 3D images at any arbitrary position without any restrictions and requires no additional procedure during the depth conversion process. Due to the lenslet model involved in the depth conversion procedure, the proposed method can broaden the flexibility of 3D image reconstruction in the integral imaging display system. We carry out the preliminary experiments to prove the feasibility of the proposed method. The experimental results reveal that the proposed method is an effective depth conversion method that allows the reconstruction of the orthoscopic 3D images at any arbitrary position.     

Compression scheme of sub-images using Karhunen-Loeve transform in three-dimensional integral imaging

In this paper, a compression scheme of sub-image-transformed elemental images using Karhunen-Loeve transform (KLT) in three-dimensional integral imaging is proposed. The proposed scheme provides improved compression efficiency by improving the similarity between elemental images using sub-image transformation. To test the proposed scheme, various elemental images of 3D objects are picked up and the compression process is carried out using KLT. From the experimental results, it is showed that the proposed compression scheme gives us an improved efficiency of 26% as compared with the conventional compression method.     

Efficient compression of motion-compensated sub-images with Karhunen-Loeve transform in three-dimensional integral imaging

An approach to highly enhance the compression efficiency of the integral images by applying the Karhunen-Loeve transform (KLT) algorithm to the motion-compensated sub-images is proposed. The sub-images transformed from the elemental images picked-up from the three-dimensional (3D) object might represent the different perspectives of the object. Thus, the similarity among the sub-images gets better than that among the elemental images, so that an improvement of compression efficiency of the sub-images could be obtained. However, motion vectors occurred among the sub-images might result in an additional increase of image data to be compressed. Accordingly, in this paper, motion vectors have been estimated and compensated in all sub-image in advance. Then the KLT algorithm was applied to these motion-compensated sub-images for compression. It is shown from some experimental results that compression efficiency of the proposed method has been improved up to 24.44%, 40.62%, respectively, on the average compared to that of the conventional KLT compression method and that of the JPEG.     

Robust image encryption by combined use of integral imaging and pixel scrambling techniques

A robust image encryption method by using the integral imaging and pixel scrambling (PS) techniques is proposed. In this method, pixels of the cover image are scrambled with the PS technique and elemental images for this scrambled image are picked up through a lenslet array. Subsequently, an encrypted image is obtained by scrambling these picked-up elemental images. Since this encrypted image has the hologram-like property of data redundancy resulted from the integral imaging scheme, while it can as well be decoded by multiple keys such as the orders of pixel scrambling and the pickup conditions of the elemental images, its security against the various attacks could be dramatically improved. Good experimental results also confirm that the proposed method could provide more enhanced robustness against data loss and Gaussian noises compared to the conventional methods.     

Improved depth extraction method of 3D objects using computational integral imaging reconstruction based on multiple windowing techniques

This paper presents an improved depth extraction method of 3D objects using computational integral imaging reconstruction (CIIR) based on the multiple windowing models. The proposed method records 3D objects using the lenslet array; and it reconstructs multiple sets of slice images from multiple CIIR methods based on the different windowing models. A depth map is then extracted by a block matching algorithm among multiple set of slice images. A preliminary experiment is carried out to show the feasibility of the proposed method. Experimental results indicate the proposed method outperforms the previous method with two windowing models.     

Enhanced compression of integral images by combined use of residual images and MPEG-4 algorithm in three-dimensional integral imaging

In this paper, we proposed a novel approach to enhance the compression rate of integral images by combined use of the residual images generated from the sub-images and the MPEG-4 algorithm. In the proposed method, elemental images picked up from a three-dimensional object are transformed into sub-images, and these sub-images are sequentially rearranged with a spiral scanning topology and the first sub-image is assigned as the reference image. Then, by sequentially computing the differences between the reference image and other consecutive sub-images, a sequence of residual images is generated. Here, the residual images together with the reference image are modeled as the consecutive video frames just like a conventional moving picture. Finally, these residual images are compressed with the MPEG-4 algorithm. Experimental results show that compression efficiency of the proposed method has been improved up to 61.56% as compared to those of the JPEG-based compression scheme and up to 151.54% as compared to those of the conventional method averagely.     

Computational integral imaging reconstruction scheme of far 3D objects by additional use of an imaging lens

In this paper, we propose a novel performance-enhanced computational integral imaging reconstruction (CIIR) scheme by additional use of an imaging lens. In the proposed scheme, elemental images can be obtained by using a simultaneous pickup scheme of far three-dimensional (3D) objects from the lenslet array in both real and virtual image fields. And additional imaging lens produces an image shift effect of 3D objects located far away from the lenslet array and improve the visual quality of reconstructed images in CIIR by overcoming limitation of pickup range in integral imaging. To show the usefulness of the proposed system, some experiments are carried out for real 3D objects and its results are presented.     

Real-time sensing and three-dimensional display of far outdoor scenes based on asymmetric integral imaging

A new asymmetric integral imaging (AII) system for real-time pickup and three-dimensional (3-D) display of far outdoor scenes based on dynamic-pixel-mapping (DPM) is proposed. DPM is a digital process to transform the elemental images captured with a lens array into the perspective-variant object images (POIs) whose structures are matched with those of display lenses, where the orders of pixels in each POI are reversely mapped, and then capture a set of virtual elemental images (EIs) at the specific depth planes from the back-propagated POIs. This DPM enables an asymmetrical use of pickup and display lens arrays, allowing the long-ranged pickup of far outdoor scenes and their resolution-enhanced 3-D reconstruction. Experiments with a pair of pickup and display lens arrays whose pitches and focal lengths are given by 7.5 mm, 30 mm and 1.2 mm, 8 mm, respectively, show that the effective pickup-range and resolution of the proposed system have been increased up to 6 m and 1600×1600 pixels, respectively, from 0.064 m and 480×480 pixels of the conventional systems employing the same pickup and display lens arrays. In addition, experiments with an implemented test bed confirms that the proposed system can provide real-time 3-D images in 25 frames per second.     

基于同心球透镜的四镜头探测器阵列拼接成像系统

为了同时实现成像系统的大视场、长焦距和高分辨率,设计了基于同心球透镜的四镜头探测器阵列拼接成像系统.首先,阐述了四镜头探测器阵列拼接方案的原理;介绍了同心球透镜的结构特点,阐述了其成像优点.然后,完成了满足实际拼接应用的同心球广角、长焦成像系统(拼接子系统)的光学设计.最后,给出了拼接子系统的像质评价并对其进行公差分析.结果表明:拼接后的系统可实现100 mm焦距和120°视场成像.该系统解决了大视场和长焦距之间的矛盾,可实现超高像素成像,相对于传统光电成像系统具有巨大的优势.     

集成成像三维显示系统显示性能的研究进展

集成成像三维显示技术是利用透镜阵列获取和显示立体图像的一种三维显示技术。本文首先综述了集成成像三维显示系统的特点,考虑其系统性能主要受分辨率、景深和观看视场角的限制,对近年来集成成像三维显示系统在增大分辨率、景深和观看视场角方面的研究进展做了综合论述,比较分析了各种改进方法的优劣。最后,对我国集成成像三维显示技术的研究现状进行了总结,并简述了本研究小组在该领域取得的若干研究成果。     

离轴型虚像成像显示系统研究

介绍了离轴型虚像显示系统的性能、结构设计和成像原理。     

Enhanced computational integral imaging system for partially occluded 3D objects using occlusion removal technique and recursive PCA reconstruction

In this paper, we propose an enhanced computational integral imaging system by both eliminating the occlusion in the elemental images recorded from the partially occluded 3D object and recovering the entire elemental images of the 3D object. In the proposed system, we first obtain the elemental images for partially occluded object using computational integral imaging system and it is transformed to sub-images. Then we eliminate the occlusion within the sub-images by use of an occlusion removal technique. To compensate the removed part from occlusion-removed sub-images, we use a recursive application of PCA reconstruction and error compensation. Finally, we generate the entire elemental images without a loss from the newly reconstructed sub-images and perform the process of object recognition. To show the usefulness of the proposed system, we carry out the computational experiments for face recognition and its results are presented. Our experimental results show that the proposed system might improve the recognition performance dramatically.     

辐射成像系统中图像转换屏与物镜耦合的分析

辐射成像系统中,射线沿闪烁体厚度方向产生的光经过镜头形成一个弥散的像。这通常是此类系统空间分辨的主要限制因素。建立了几何光学成像模型,描述了近心光路中此图像的空变特性。用点扩散函数均方根半径表征系统空间分辨性能,给出了图像点扩散函数均方根半径的表达式,其与闪烁体厚度、折射率、镜头相对孔径、成像倍率、射线入射点相对位置直接相关。将硅酸镥晶体3维发光强度分布与镜头进行耦合,分析了闪烁体发光强度分布对耦合的影响。采用点扩散函数均方根半径为最小的原则,建立了一个推导闪烁体相对于物镜放置在最佳位置的方法。     

辐射成像系统中图像转换屏与物镜耦合的分析

辐射成像系统中,射线沿闪烁体厚度方向产生的光经过镜头形成一个弥散的像。这通常是此类系统空间分辨的主要限制因素。建立了几何光学成像模型,描述了近心光路中此图像的空变特性。用点扩散函数均方根半径表征系统空间分辨性能,给出了图像点扩散函数均方根半径的表达式,其与闪烁体厚度、折射率、镜头相对孔径、成像倍率、射线入射点相对位置直接相关。将硅酸镥晶体3维发光强度分布与镜头进行耦合,分析了闪烁体发光强度分布对耦合的影响。采用点扩散函数均方根半径为最小的原则,建立了一个推导闪烁体相对于物镜放置在最佳位置的方法。     

Computational integral imaging reconstruction method of 3D images using pixel-to-pixel mapping and image interpolation

In this paper, we propose a novel computational integral imaging reconstruction (CIIR) method to improve the visual quality of the reconstructed images using a pixel-to-pixel mapping and an interpolation technique. Since an elemental image is magnified inversely through the corresponding pinhole and mapped on the reconstruction output plane based on pinhole-array model in the conventional CIIR method, the visual quality of reconstructed output image (ROI) degrades due to the interference problem between adjacent pixels during the superposition of the magnified elemental images. To avoid this problem, the proposed CIIR method generates dot-pattern ROIs using a pixel-to-pixel mapping and substitutes interpolated values for the empty pixels within the dot-pattern ROIs using an interpolation technique. The interpolated ROIs provides a much improved visual quality compared with the conventional method because of the exact regeneration of pixel positions sampled in the pickup process without interference between pixels. Moreover, it can enable us to reduce a computational cost by eliminating the magnification process used in the conventional CIIR. To confirm the feasibility of the proposed system, some experiments are carried out and the results are presented.