UCHT-based complex sequences for asynchronous CDMA system

The use of orthogonal spreading codes has attracted much attention due to their ability to suppress interference from other users, compared with the nonorthogonal sequences in the synchronous case. In this paper, new sets of orthogonal sequences derived from the unified complex Hadamard transforms (UCHTs) are investigated. Various correlation properties of the sequences are mathematically derived and analyzed. It is shown that some UCHT sequences provide better autocorrelation properties than orthogonal Walsh-Hadamard sequences. Performance comparisons between UCHT sequences, Gold, small set of Kasami, and m-sequences show that some UCHT sequences outperform these well-known spreading sequences under simulation of systems in the presence of multiple access interference and additive white Gaussian noise.     

Properties and relations for fast linearly independent arithmetic transforms

New fast linearly independent arithmetic (LIA) transforms are introduced here which can be used to represent any functions of binary variables. The transforms are grouped into classes where consistent formulas relating forward and inverse transform matrices are obtained. All the presented transforms have the same computational cost, which is lower than the computational cost of the well-known fixed polarity arithmetic transforms. General classifications and fast forward and inverse transform definitions for all the fast LIA transforms are given. Various properties and mutual relations that exist for the different transforms and their corresponding spectra are also shown. The presented relations and properties reduce the computational cost of finding the best LIA polynomial expansion based on the new transforms.     

X-Charts versus X / MR Chart Combinations: IID Cases and Non-IID Cases

The effectiveness of the X-Chart alone (X-only Chart) is compared to that of the Individuals and Moving Range Chart Combination (X/MR Charts), in terms of Average Run Length (ARL) after designing for a common “all OK” (in control) ARL. Comparison is made under five different non-standard conditions, including both iid and non-iid circumstances. We conclude that adding the Moving Range chart to an X-chart, while generally not helpful for detecting iid departures from standard conditions, can be beneficial in detecting some non-iid conditions.     

A fine granular scalable to lossless audio coder

This paper presents Advanced Audio Zip (AAZ), a fine grained scalable to lossless (SLS) audio coder that has recently been adopted as the reference model for MPEG-4 audio SLS work. AAZ integrates the functionalities of high-compression perceptual audio coding, fine granular scalable audio coding, and lossless audio coding in a single framework, and simultaneously provides backward compatibility to MPEG-4 Advanced Audio Coding (AAC). AAZ provides the fine granular bit-rate scalability from lossy to lossless coding, and such a scalability is achieved in a perceptually meaningful way, i.e., better perceptual quality at higher bit-rates. Despite its abundant functionalities, AAZ only introduces negligible overhead in terms of lossless compression performance compared with a nonscalable, lossless only audio coder. As a result, AAZ provides a universal yet efficient solution for digital audio applications such as audio archiving, network audio streaming, portable audio playing, and music downloading which were previously catered for by several different audio coding technologies, and eliminates the need for any transcoding system to facilitate sharing of digital audio contents across these application domains.     

Frequency Region-Based Prioritized Bit-Plane Coding for Scalable Audio

A perceptually enhanced prioritized bit-plane audio coding algorithm is presented in this paper. According to the energy distribution in different frequency regions, the bit-planes are prioritized with optimized parameters. Based on the statistical modeling of the frequency spectrum, a much more simplified implementation of prioritized bit-plane coding is integrated with the recent release of MPEG-4 scalable lossless (SLS) audio coding structure by replacing the sequential bit-plane coding in the enhancement layer. With zero extra side information, trivial added complexity, and modification to the original SLS structure, extensive experimental results show that the perceptual quality of SLS with noncore and very low core bit-rate is improved significantly in a wide range of bit-rate combinations. Fully scalable audio coding up to lossless with much enhanced perceptual quality is thus achieved.     

Object recognition by discriminative combinations of line segments, ellipses, and appearance features

We present a novel contour-based approach that recognizes object classes in real-world scenes using simple and generic shape primitives of line segments and ellipses. Compared to commonly used contour fragment features, these primitives support more efficient representation since their storage requirements are independent of object size. Additionally, these primitives are readily described by their geometrical properties and hence afford very efficient feature comparison. We pair these primitives as shape-tokens and learn discriminative combinations of shape-tokens. Here, we allow each combination to have a variable number of shape-tokens. This, coupled with the generic nature of primitives, enables a variety of class-specific shape structures to be learned. Building on the contour-based method, we propose a new hybrid recognition method that combines shape and appearance features. Each discriminative combination can vary in the number and the types of features, where these two degrees of variability empower the hybrid method with even more flexibility and discriminative potential. We evaluate our methods across a large number of challenging classes, and obtain very competitive results against other methods. These results show the proposed shape primitives are indeed sufficiently powerful to recognize object classes in complex real-world scenes.     

Natural and Seamless Image Composition With Color Control

While the state-of-the-art image composition algorithms subtly handle the object boundary to achieve seamless image copy-and-paste, it is observed that they are unable to preserve the color fidelity of the source object, often require quite an amount of user interactions, and often fail to achieve realism when there exists salient discrepancy between the background textures in the source and destination images. These observations motivate our research towards color controlled natural and seamless image composition with least user interactions. In particular, based on the Poisson image editing framework, we first propose a variational model that considers both the gradient constraint and the color fidelity. The proposed model allows users to control the coloring effect caused by gradient domain fusion. Second, to have less user interactions, we propose a distance-enhanced random walks algorithm, through which we avoid the necessity of accurate image segmentation while still able to highlight the foreground object. Third, we propose a multiresolution framework to perform image compositions at different subbands so as to separate the texture and color components to simultaneously achieve smooth texture transition and desired color control. The experimental results demonstrate that our proposed framework achieves better and more realistic results for images with salient background color or texture differences, while providing comparable results as the state-of-the-art algorithms for images without the need of preserving the object color fidelity and without significant background texture discrepancy.     

Using edge direction information for measuring blocking artifacts of images

Block-based transform coding is the most popular approach for image and video compression. The objective measurement of blocking artifacts plays an important role in the design, optimization, and assessment of image and video coding systems. This paper presents a new algorithm for measuring blocking artifacts in images and videos. Instead of using the traditional pixel discontinuity along the block boundary, we use the edge directional information of the images. The new algorithm does not need the exact location of the block boundary thus is invariant to the displacement, rotation and scaling of the images. Experiments on various still images and videos show that the new blockiness measure is very efficient in terms of computational complexity and memory usage, and can produce blocking artifacts measurement consistent with subjective rating.     

Complex decision diagrams

Complex decision diagrams to represent integer-valued functions in the form of complex Hadamard transforms and spectra are introduced. With the distinctive and unique properties of the transform, the novel complex decision diagrams could be further simplified by reduction rules and a half-spectra theorem that will lead to a more compact representation