34732275
Signal extrapolation based on wavelet transform
The Papoulis-Gerchberg (PG) algorithm is used for band-limited signal extrapolation. The PG algorithm is generalized to signals in wavelet subspaces. The generalized PG algorithm is considered for both continuous and discrete time signals. Its convergence is investigated. Numerical examples show its performance.<<ETX>>
28495632
Iterative signal extrapolation algorithms with wavelets
A generalized Papoulis-Gerchberg (PG) algorithm for signal extrapolation based on the wavelet representation has been recently proposed by Xia, Kuo and Zhang. In this research, we first show that the generalized PG algorithm converges to the minimum norm solution when the wavelet bases are semi-orthogonal (or known as the prewavelet). However, the generalized PG algorithm converges slowly in numerical implementation. To accelerate the convergence rate, we formulate the discrete signal extrapolation problem os a two-step process and apply the steepest descent and conjugate gradient methods for its solution. Numerical experiments are given to illustrate the performance of the proposed algorithms.<<ETX>>
9519178
Progressive image indexing and retrieval based on embedded wavelet coding
A complete wavelet-based image storage and indexing system is proposed in this research. The proposed indexing features take account of the color, brightness, texture, frequency, and spatial information of a given query image. All features can be naturally extracted as a byproduct during the image compression. Since coding and indexing are integrated in an unified framework in the proposed system, the database management is greatly simplified. Extensive experimental results are given to demonstrate the retrieval performance of the new approach.
448363
A multiscale error diffusion technique for digital halftoning
A new digital halftoning technique based on multiscale error diffusion is examined. We use an image quadtree to represent the difference image between the input gray-level image and the output halftone image. In iterative algorithm is developed that searches the brightest region of a given image via "maximum intensity guidance" for assigning dots and diffuses the quantization error noncausally at each iteration. To measure the quality of halftone images, we adopt a new criterion based on hierarchical intensity distribution. The proposed method provides very good results both visually and in terms of the hierarchical intensity quality measure.
14807272
Progressive compression of 3D graphic models
A progressive coding method which encodes a 3D graphic model into an embedded bit stream is investigated in this research. The coder first encodes the coarsest resolution of the model, and then includes the finer details gradually. The embedding property allows the decoder to terminate the decoding at an arbitrary position in the compressed bit stream, and a more accurate model can be obtained when more bits are decoded. Numerical experiments are provided to demonstrate the excellent rate distortion performance and progressive compression performance of the new method.
1584599
Embedded coding of 3D graphic models
A progressive compression method which encodes a 3D graphic models into an embedded bit stream is investigated. The coder first encodes the coarsest resolution of the model, and then includes the information of finer details gradually. A rate-distortion model is used in the integration of different types of bit streams into a single embedded bit stream to optimize the overall coding performance. This embedding property can be applied to progressive transmission, multi-resolution editing and level-of-detail control. Numerical experiments are provided to demonstrate the excellent rate-distortion performance of the proposed method.
12549772
Designing an evaluation method for security user interfaces: lessons from studying secure wireless network configuration
: / 28 Ten or 20 years ago, evaluating security products was not as much of a problem as it is today. Systems were managed by people able—and willing—to master the complexities. However, with the proliferation of personal computing devices and network connectivity in the home, systems are now regularly managed by nonexperts. Each system needs to be secured by each user in each home. Therefore designing effective, unbiased evaluation methods for consumer products is one of the first steps in improving both users’ experiences and their security practices. Evaluating the usability of security is a challenge. A common question evaluators face is: “How do I test whether users will configure and use a product securely?” In this article, we outline problems we encountered in evaluating secure wireless network configuration and examine the assumptions many user study methods make, but which may not hold for security.
24413432
A hybrid BMC/OBMC motion compensation scheme
In this paper, we propose a hybrid scheme which incorporates the block motion compensation (BMC) scheme in the overlapped block motion compensation (OBMC) scheme. The main objective of this hybrid scheme is to improve a pure OBMC system with a lower motion bit rate and a lower search complexity while retaining about the same PSNR level. With this scheme, the encoder can determine the block mode under the tradeoff of complexity and visual quality. Furthermore, the motion bit rate can be reduced by smoothing the motion field of BMC blocks during motion search. Experimental results show that the complexity of both the encoder and the decoder is reduced while the visual quality remains as good as the pure OBMC system.