Xiao-Wei Li

Designing Three-Dimensional Cellular Automata Based Video Authentication With an Optical Integral Imaging Generated Memory-Distributed Watermark

Integral imaging for image watermarking is attracting a great deal of interest as it provides high processing speed and data redundancy property. Traditional video watermarking algorithms are mostly based on discrete transform domains, such as the discrete cosine transform and discrete wavelet transform. Most of these algorithms generally provide one transform plane for watermarking. In this paper, we propose a video watermarking by employing three-dimensional (3-D) cellular automata (CA) transform and perfect-reconstruction integral imaging (PRII). Compared to the existing works, the main strength of this paper is to utilize a 3-D CA transform to produce multiple transform planes for watermark embedding, so that greatly improve the security; decompose watermark into a series of elemental images using integral imaging to enhance the robustness; and employ perfect-reconstruction filter into the iterative back-projection process thus resolving the ringing artifacts problems. Experimental results show that the proposed PRII-based watermarking method outperforms other similar watermarking methods and is robust to a wide range of attacks, e.g., Gaussian noise, salt and pepper noise, frame clipping, JPEG compression, and median filter attack.

Modified integral imaging reconstruction and encryption using an improved SR reconstruction algorithm

Abstract We propose a monospectral image encryption method in which the multispectral color image acquisition by using heterogeneous monospectral cameras. Because the captured monospectral elemental images (EIs) belongs to grayscale image, it is means that the captured EIs can be directly encrypted by the proposed encoding method. Subsequently, the linear cellular automata (CA) and hyperchaotic encoding algorithm are employed to encrypt the captured EIs. Different from previous methods, the proposed method can directly encrypt the multispectral color information rather than having to divide into three color channels (R, G and B), thereby, the proposed method can greatly reduce the encryption calculation.

Two-Step Integral Imaging Coding Based Three-Dimensional Information Encryption Approach

We propose a two-step integral imaging coding based three-dimensional (3D) information encryption approach in this paper. In this approach, a synthetic aperture integral imaging system is applied to acquire a set of parallax images including spatial and angular information of 3D scene. In the encryption process, two-step coding is performed. In the first step, the acquired parallax images are encrypted firstly by double random-phase coding in the Fresnel domain. In the second step, these encrypted parallax images are encoded into a cipher image by mapping algorithm which is used to generate elemental image array of integral imaging. In the decryption process, an inverse operation is performed. The experimental results demonstrate the feasibility, security, and robustness of the proposed approach.

Wavelet-based iterative perfect reconstruction in computational integral imaging

We propose a new computational integral imaging (CII) method via the iterative perfect reconstruction technique to improve the visual quality of reconstructed 3D scenes. As is well known, images reconstructed by CII suffer from artifacts and, as a result, degradation of visual quality. As solutions to this problem, the regularization and iterative back-projection (IBP)-based super-resolution (SR) reconstruction algorithms have been shown to be effective for high-visual-quality reconstruction. However, computation of the regularization algorithm is very expensive, and the IBP algorithm is very sensitive to noise in the deblurring process. To address these challenges, we propose an iterative perfect reconstruction algorithm that addresses the issues of low visual quality and noise sensitivity. Experimental results indicate that our proposed method outperforms the conventional SR reconstruction-based CII methods.

Computer-generated hologram generation method to increase the field of view of the reconstructed image

In this paper, a computer-generated hologram (CGH) generation method is proposed to increase the field of view (FOV) in the holographic display. The CGH is generated through accumulating interference patterns of all object points. The size of each interference pattern is equal to the sum of the size of the recorded object and the spatial light modulator (SLM), so the size of the interference pattern is increased. The position of the interference pattern is related to that of the corresponding recorded object point. In the reconstruction process, three SLMs in a planar configuration are used to load the CGH. The seams between the SLMs are eliminated by beam splitters. Meanwhile, the boundaries of the diffraction light of all interference patterns are parallel with each other. Compared with the holographic display method using one SLM, the experiments demonstrate that the proposed method can reduce the demand for viewing distance and expand the FOV obviously in the horizontal direction, especially for the large-sized recorded object.

Optical encryption via monospectral integral imaging

Optical integral imaging (II) uses a lenslet array and CCD sensor as the 3D acquisition device, in which the multispectral information is acquired by a color filter array (CFA). However, color crosstalk exists in CFA that diminishes color gamut, resulting in the reduced resolution. In this paper, we present a monospectral II encryption approach with a monospectral camera array (MCA). The monospectral II system captures images with the MCA that can eliminate color crosstalk among the adjacent spectral channels. It is noteworthy that the captured elemental images (EIs) from the colored scene belong to grayscale; the colored image encryption is converted to grayscale encryption. Consequently, this study will significantly save the calculation load in image encoding and decoding (nearly reduced 2/3) compared with the similar works. Afterwards, an optimized super-resolution reconstruction algorithm is introduced to improve the viewing resolution.