共查询到20条相似文献,搜索用时 31 毫秒
1.
Visual cryptography is expected to have various applications since it has potential for visual decoding. However, there are
still few practical applications. One reason for this is the difficulty of superposition to decode. To solve the alignment
difficulty, we propose an information hiding method which can be physically decode by superimposing a checkered pattern. Superimposing
a checkered pattern can also be considered as a kind of image sampling process, and a decoding experiment using an ordinary
compact digital camera is presented. 相似文献
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A well-designed parallax barrier autostereoscopic display can produce high-quality stereo images with little crosstalk or even without crosstalk in the stereo viewing zones. The concept of stereo image quality factor was defined to indicate the stereo viewing zone of an autostereoscopic display. According to the structure and principle of the display, the formulae of stereo image quality factor were deduced. Simulated program was developed to calculate stereo image quality factor. The simulated results of stereo image quality factor for a 19-in autostereoscopic display monitor show that stereo image quality factor can indicate the stereo viewing zone of autostereoscopic displays. The simulated results also show that the value of stereo image quality factor is equal to 1 at only few positions where viewers can see very good stereo images without crosstalk. And the viewers who stay at the optimal viewing distance can see the best stereo images on the display screen. The research of the stereo viewing zone helps in the design of such autostereoscopic display devices with little or without crosstalk. 相似文献
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We developed a technique of three-dimensional (3-D) display for distant viewing of a 3-D image without the need for special glasses. The photobased integral photography (IP) method allows precise 3-D images to be displayed at long viewing distances without any influence from deviated or distorted lenses in a lens array. We calculate elemental images from a referential viewing area for each lens and project the corresponding result images to photographic film through each lens. We succeed in creating an image display that appears to have three dimensionality even when viewed from a distance, with an image depth of 5.7 m or more in front of the display and 3.5 m or more behind the display. To the best of our knowledge, the long-distance IP display presented here is technically unique because it is the first report of generation of an image with such a long viewing distance. 相似文献
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为了对不同集成成像系统三维显示应用中的视觉分辨效果进行表征, 提出了一种基于人眼视觉的集成成像三维显示分辨率的分析比较方法. 通过分析集成成像三维显示系统的分辨率与人眼在最佳显示观看距离下分辨本领的关系, 定义了相对分辨率参数, 分析了其与集成成像三维显示实际观看时视觉分辨效果的关系. 研究结果表明, 透镜阵列的大小对集成成像三维显示的视觉分辨效果有重要的影响. 针对两个系统实例的理论计算结果表明, 系统间的相对分辨率参数差异是传统分辨率差异的1.75倍, 实验结果与理论分析一致. 该研究方法对三维显示分辨率的评价有一定的指导意义. 相似文献
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John Fredy Barrera Rodrigo Henao Myrian Tebaldi Roberto Torroba Nstor Bolognini 《Optik》2008,119(3):139-142
The purpose of this research is to develop an undercover multiplexing technique to give additional protection for optical information encryption. We employ the double random phase mask as our basic optical encryption system. The holographic storage medium of choice is a photorefractive crystal. To achieve the multiplexing we use the aperture size of the pupil in the optical system, as it governs the speckle size. We introduce such variation in order to produce a decorrelation between two consecutively stored speckle patterns. Each stored speckle pattern is associated to an input encrypted image, thus producing a multiplexing of the encrypted information. We implement this operation without altering the setup architecture and the random phase masks. This multiplexing is our undercover operation to encipher a true code behind a fake code. Under this approach, the user can only recover the bulk information stored in the volume hologram. However, he cannot recover the true code without the additional information on the pupil size key, even if accessed in position of the original decoding mask. 相似文献
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光学并行实现模糊逻辑图像处理 总被引:2,自引:2,他引:0
提出和验证一种基于偏振-空间编码方案和多重成像技术的光学方法来实现模糊逻辑图像处理,系统中,模糊变量和它们的补被编码为空间正交分布的两个偏振状态。通过对透镜阵列状态的编程,可以实现两个模糊图像间的模糊逻辑操作。本系统中,两个输入图像被偏振编码为8个编码图像作为输入图像,系统是空不变系统,不需要取阈装置和解码过程,通过引进取阈装置,可以在一层系统中实现两个图像间更为复杂的模糊逻辑操作,并给出了实验结果。 相似文献
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Nam Kim Md. Ashraful Alam Le Thanh Bang Anh-Hoang Phan Mei-Lan Piao Munkh-Uchral Erdenebat 《中国光学快报(英文版)》2014,12(6):60005-20
Light field displays comprise three-dimensional (3D) visual information presentation devices capable of providing realistic and full parallax autostereoscopic images. In this letter, the recent advances in the light field displays based on integral imaging (II) and holographic techniques are presented. Several advanced approaches to demonstrate the light field displays including viewing angle enhancement techniques of the II display, a fast hologram generation method using graphics processing unit (GPU) and multiple WRPs, and a holographic microscopy to display the living cells are reported. These methods improve some important constraints of the light field displays and add new features. 相似文献
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《中国物理快报》2017,(11)
We propose to realize visual cryptography in an indirect way with the help of diffractive optics, the pure-amplitude keys being substituted with the phase-only keys that are invisible for common-used intensity detectors, leading to the significantly enhanced security and improved usability for practice. Three typical realizations are provided by using static or dynamic diffractive optical elements, and the new concept of invisible visual cryptography(IVC)may be established. This concept is demonstrated by a compact opto-electronic system with only one spatial light modulator within time-delayed exposure, maintaining the fast speed of decryption and no requirement to the calculation of decryption in conventional visual cryptography. Further, IVC shows the immunity to noises and good information capacity, which is partly inherited from diffractive optics. IVC might suggest a new strategy for visual cryptography with the respective of diverse realizations, such as opto-electronic or even bio-chemical or other methods. 相似文献
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三维显示是人类获取身临其境视觉信息的有效途径,其中全息技术能够提供人眼所需的全部深度信息,被认为是理想的三维显示方式.然而受目前显示器件的限制,如可刷新调制器件的时间-空间(时空)带宽积受限、海量数据云处理速率限制、图像质量不高的问题等,全息显示技术的发展进入了瓶颈期.为了提高显示质量、扩大时空带宽积、提升系统性能,需要发展崭新的全息显示器件,从根本上解决目前遇到的问题.超颖材料、超构表面以及二维材料等诸多新颖材料的涌现为全息显示带来新的机遇.超颖材料(表面)通过特殊设计,利用远小于波长的超构单元实现对波前各向同性或各向异性的振幅与相位的特异调控,进而将全息信息映射到超颖材料(表面)全息显示器件上,通过调控光波实现各种显示.发展可刷新的超构(表面、二维)材料并应用于动态全息显示中是未来的重要方向.虽然现有的新颖器件还面临着各种问题,但它们可为全息显示的发展提供潜在的可行性和新的视角与发展动力. 相似文献
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In this paper, we have described a simple and secure double random phase encoding and decoding system to encrypt and decrypt a two-dimensional gray scale image. We have used jigsaw transforms of the second random phase mask and the encrypted image. The random phase mask placed in the Fourier plane is broken into independent non-overlapping segments by applying the jigsaw transform. To make the system more secure, a jigsaw transform on the encrypted image is also carried out. The encrypted image is also broken into independent non-overlapping segments. The jigsaw transform indices of random phase code and the encrypted image form the keys for the successful retrieval of the data. Encrypting with this technique makes it almost impossible to retrieve the image without using both the right keys. Results of computer simulation have been presented in support of the proposed idea. Mean square error (MSE) between the decrypted and the original image has also been calculated in support of the technique. 相似文献
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The Virtual Retinal Display (VRD) is a visual display that scans modulated laser light on to the retina of the viewer's eye to create an image. Maximum permissible exposures (MPE) have been calculated for the VRD in both normal viewing and possible failure modes. The MPE power levels are compared to the measured power that enters the eye while viewing images with the VRD. The power levels indicate that the VRD is safe in both normal operating mode and in failure modes. 相似文献
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We analyze the distribution of secure keys using quantum cryptography based on the continuous variable degree of freedom of entangled photon pairs. We derive the information capacity of a scheme based on the spatial entanglement of photons from a realistic source, and show that the standard measures of security known for quadrature-based continuous variable quantum cryptography (CV-QKD) are inadequate. A specific simple eavesdropping attack is analyzed to illuminate how secret information may be distilled well beyond the bounds of the usual CV-QKD measures. 相似文献
16.
Viewing-angle-enhanced integral imaging by lens switching 总被引:1,自引:0,他引:1
In spite of the many advantages of integral imaging, its narrow viewing angle has been a disadvantage. We propose a method to enhance the viewing angle of integral imaging by opening and shutting each lens in the array (i.e., the elemental lenses) sequentially. We prove our idea by using a mask that has a pattern of an on-off vertical array of apertures. Moving the mask prevents the aliasing of a neighboring lens. Thus image overlap or image flipping is reduced and the viewing angle of the system is increased. 相似文献
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Improved viewing resolution of three-dimensional integral imaging by use of nonstationary micro-optics 总被引:4,自引:0,他引:4
We propose the use of synchronously moving micro-optics (lenslet arrays) for image pickup and display in three-dimensional integral imaging to overcome the upper resolution limit imposed by the Nyquist sampling theorem. With the proposed technique, we show experimentally that the viewing resolution can be improved without reducing the three-dimensional viewing aspect of the reconstructed image. 相似文献
19.
We introduce the technique to get the undercover multiplexing of a set of encrypted data. We base the general encryption approach on the double-random phase encoding method. We made the encoding phase masks with scaled versions of a master speckle pattern. A fake object is encrypted using a master mask made with the master speckle pattern. Each subsequent object to be hidden is associated to a suitable different scaled version of the original master mask. We apply the term suitable referring to avoid a possible cross-talk in the final decrypted images. All encrypted data are multiplexed to form a single message. This operation enables the true information undercover. We openly send this undercover message along with the master mask. Via separated private channels, we send the information on the actual scaling for each encrypting mask to the authorized users. Unauthorized users attempting to recover the information by using the master mask alone, get the fake object. During decryption of the multiplexed message, we only reconstruct the object that matches the predetermined scaled version of the master mask used to encode it. We show results that confirm our approach. 相似文献
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A low-dynamic tone-compression technique is developed for realistic image rendering that can make three-dimensional (3D) images similar to realistic scenes by overcoming brightness dimming in the 3D display mode. The 3D surround provides varying conditions for image quality, illuminant adaptation, contrast, gamma, color, sharpness, and so on. In general, gain/offset adjustment, gamma compensation, and histogram equalization have performed well in contrast compression; however, as a result of signal saturation and clipping effects, image details are removed and information is lost on bright and dark areas. Thus, an enhanced image mapping technique is proposed based on space-varying image compression. The performance of contrast compression is enhanced with complex adaptation in a 3D viewing surround combining global and local adaptation. Evaluating local image rendering in view of tone and color expression, noise reduction, and edge compensation confirms that the proposed 3D image-mapping model can compensate for the loss of image quality in the 3D mode. 相似文献