Wafer defect detection often relies on accurate image registration of source and reference images obtained from neighboring dies. Unfortunately, perfect registration is generally impossible, due to pattern variations between the source and reference images. In this paper, we propose a defect detection procedure, which avoids image registration and is robust to pattern variations. The proposed method is based on anisotropic kernel reconstruction of the source image using the reference image. The source and reference images are mapped into a feature space, where every feature with origin in the source image is estimated by a weighted sum of neighboring features from the reference image. The set of neighboring features is determined according to the spatial neighborhood in the original image space, and the weights are calculated from exponential distance similarity function. We show that features originating from defect regions are not reconstructible from the reference image, and hence can be identified. The performance of the proposed algorithm is evaluated and its advantage is demonstrated compared to using an anomaly detection algorithm.

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Defect detection in patterned wafers using anisotropic kernels

In this paper, an efficient and robust image watermarking scheme based on lifting wavelet transform (LWT) and QR decomposition using Lagrangian support vector regression (LSVR) is presented. After performing one level decomposition of host image using LWT, the low frequency subband is divided into 4?×?4 non-overlapping blocks. Based on the correlation property of lifting wavelet coefficients, each selected block is followed by QR decomposition. The significant element of first row of R matrix of each block is set as target to LSVR for embedding the watermark. The remaining elements (called feature vector) of upper triangular matrix R act as input to LSVR. The security of the watermark is achieved by applying Arnold transformation to original watermark to get its scrambled image. This scrambled image is embedded into the output (predicted value) of LSVR compared with the target value using optimal scaling factor to reduce the tradeoff between imperceptibility and robustness. Experimental results show that proposed scheme not only efficient in terms of computational cost and memory requirement but also achieve good imperceptibility and robustness against image processing operations compared to the state-of-art techniques.

LWT- QR decomposition based robust and efficient image watermarking scheme using Lagrangian SVR

Commercial markets employ digital right management (DRM) systems to protect valuable high-definition (HD) quality videos. DRM system uses watermarking to provide copyright protection and ownership authentication of multimedia contents. We propose a real-time video watermarking scheme for HD video in the uncompressed domain. Especially, our approach is in aspect of practical perspectives to satisfy perceptual quality, real-time processing, and robustness requirements. We simplify and optimize human visual system mask for real-time performance and also apply dithering technique for invisibility. Extensive experiments are performed to prove that the proposed scheme satisfies the invisibility, real-time processing, and robustness requirements against video processing attacks. We concentrate upon video processing attacks that commonly occur in HD quality videos to display on portable devices. These attacks include not only scaling and low bit-rate encoding, but also malicious attacks such as format conversion and frame rate change.

Practical, Real-Time, and Robust Watermarking on the Spatial Domain for High-Definition Video Contents

This paper is to propose a digital watermarking to protect the ownership of a video content which is compressed by H.264/AVC main profile. This scheme intends to be performed during the CABAC (Context-based Adaptive Binary Arithmetic Coding) process which is the entropy coding of the main profile. It uses the contexts extracted during the context modeling process of CABAC to position the watermark bits by simply checking the context values and determining the coefficients. The watermarking process is also as simple as replacing the watermark bit with the LSB (Least Significant Bit) of the corresponding coefficient to be watermarked. Experimental results from applying this scheme and attacking in various ways such as blurring, sharpening, cropping, Gaussian noise addition, and geometrical modification showed that the watermark embedded by this scheme has very high imperceptibility and robustness to the attacks. Thus, we expect it to be used as a good watermarking scheme, especially in the area that the watermarking should be performed during the compression process with requiring minimal amount of process for watermarking.

Low-Complexity Watermarking Based on Entropy Coding in H.264/AVC

In this study, a robust, secure forensic marking algorithm was implemented using processes for generating holograms of 2D barcodes containing copyright information and embedding the holograms in the discrete wavelet transform- (DWT-) discrete fractional random transform (DFRNT) domain. In the proposed algorithm, the off-axis holograms of the 2D barcodes in which information is hidden are robust against attacks and are embedded in the transformed domains of the original images. The DFRNT enhances security by randomly mixing information so that it is embedded in unpredictable positions in certain frequency spaces. Therefore, DFRNT was combined with DWT and then used as a dual domain to ensure simultaneous robustness and security. Different holograms were produced with little signal interference by changing the coordinate values and separation angles, thereby ensuring security as well as enabling the embedding of multiple holograms in one image. The algorithm was also designed so that bit errors occurring during detection could be corrected by the self-error correction function of 2D barcodes. Its robustness was examined in several experiments, including compression, noise addition, and rotation experiments. The detection bit errors for all 2D barcodes used in the experiments were less than 3%. This confirms that the algorithm can accurately extract hidden information from detected 2D barcodes.

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Secure Image Forensic Marking Algorithm using 2D Barcode and Off-axis Hologram in DWT-DFRNT Domain

This paper propose an audio digital watermarking algorithm based on the wavelet transform (WT) and the complex cepstrum transform (CCT). The algorithm realized to embed a binary image watermark into the audio signal and improved the imperceptibility of watermarks. Experimental results show that this algorithm has a better robustness against common signal processing such as noise, filtering, resampling and lossy compression.

A digital audio watermark embedding algorithm with WT and CCT

As an effective method to provide copyright protection for digital media, digital watermarking has drawn extensive attention recently. The paper proposes a scheme of digital watermarking based on the modulation transfer function (MTF) of the human visual system(HVS). The experimental results demonstrate its better unification between the watermarking robustness and watermarking invisibility, the watermarking with the proposed scheme is robust against noise interference and commonly used image technique.

Watermarking for the digital images based on model of human perception

In this paper, analytical and numerical methods are used t o study cross_phase modulational instability. Firstly, by use of coup led nonlinear Schrdinger equation, we have studied the cross_phase modulation i nstability in the normal and anomalous dispersion fiber links of wavelength divi sion multiplexed system with an active amplifier, when the amplitude is perturbed. Se condly, m aking use of the split step Fourier transform and Monte_Carlo method, we simulat ed the cross_phase modulation instability in active normal and anomalous dispers ion fibers with fluctuation of phase noise. Comparison between the above met hods shows that the results agree with each other.

Cross-phase modulational instability in fiber link wit h an active optical amplifier*

Periodically spaced amplifiers along a transoceanic fiber links provide the phas e_matching condition for four_wave_mixing because of Kerr nonlinearity. Both ana lytic method and numerical method are used to study the cross_phase modulational sideband instability in fiber links with periodical lump amplifiers. In the ana lytic method, the gain of sideband instability is obtained. In the numerical met hod, by use of split_step Fourier transform method, the frequency spectra of out put optical pulses are obtained in normal and anomalous fiber links, and there a re sidebands in the spectrum configuration. By comparison of the results from tw o the methods, they are constant with each other.

Cross-phase modulational sideband instability in wavelength-division-multiplexing system with periodic lumped amplifiers

Dispersion management is a technology that alternately and periodically uses fibers with opposite dispersion sign in wavelength-division multiplexing link, thus the path averaged dispersion coefficient over each period is close to zero. This paper studies the cross-phase modulational sideband instability in chain of periodic dispersion managed and lumped amplified fiber link. Analytisis and numerical simulation are applied to show that there are multi-sidebands in the dispersion managed fiber link if the path averaged dispersion exhibits the abnormal dispersion, while there is only the lowest order if the path averaged dispersion exhibits the normal dispersion. The results of analytical and numerical simulation methods are consistent.

Theoretical analysis of cross-phase modulational sideband instability in wavelength-division multiplexed system with periodic dispersion managed fiber links

Li Qi-Liang

Papers

A digital audio watermark embedding algorithm with WT and CCT

Watermarking for the digital images based on model of human perception

Cross-phase modulational instability in fiber link wit h an active optical amplifier*

Cross-phase modulational sideband instability in wavelength-division-multiplexing system with periodic lumped amplifiers

Theoretical analysis of cross-phase modulational sideband instability in wavelength-division multiplexed system with periodic dispersion managed fiber links