Bandwidth efficient concatenated coding schemes

Concatenated coded modulation is a powerful method for constructing coding schemes with large coding gain and low decoding complexity. For the concatenated scheme, the outer code has redundancy and the overall transmission rate is reduced. The problem of bandwidth expansion can be overcome by two procedures. First, the code rate of inner codes is increased with a special coding design. Second, a two-level concatenated scheme is constructed to compensate the rate loss. This way, the low-complexity concatenated coded modulation schemes can be designed without bandwidth expansion as compared with the uncoded scheme.     

Adaptive fractal image coding in subband domain

Abstract

In this paper, we propose and evaluate a method for fractal image coding in the subband domain. The subband decomposition scheme acts as a classifier, which can efficiently reduce encoding time. The proposed fractal image coding scheme is an adaptive one. The adaptability is based on the variance of each subband. At each subband, the scheme adaptively sets the map block size that should be encoded. In addition, the domain blocks are adaptively restricted to the neighborhood of their respective range block. Simulation results show that good picture quality of the coded image is obtained at 0.370 bpp. It also indicates that such an adaptive scheme makes a better trade‐off between the required bit rate and picture quality than a fixed size one. Moreover, the adaptive shceme can save a large amount of time.     

Genetic coding of image on synthetic peptides

The main objective of this study is to extend the potentialities of bio‐computing and the tools of molecular genetics to storage, indexing, and digital image processing. The first approach is to carry out the direct coding of the digital image, with the four RNA bases A, G, C, and U. Secondly, we study the possibilities of information rearrangement in image content, from the RNA concept, by a specific preprocessing. The illustration of the potential of this process is carried out with a presegmented image. Finally, the advantages and the difficulties of the direct use of bioengineering in digital imagery will be evoked. © 2005 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 15, 168–171, 2005     

Low-complexity low-memory energy-efficient image coding for wireless image sensor networks

Wireless image sensor networks are capable of sensing, processing and transmitting the image in hard-to-access regions without expensive network infrastructure and will have great contribution in Internet of Things. These networks are resource constraint systems with limited memory, energy, processing speed and bandwidth. Low computational energy and communication energy will improve the lifetime of these resource-limited networks. In this paper, an energy-efficient low-memory and low-bitrate image coding is designed exclusively for low-power camera-equipped sensor node. The performance of the proposed image coder is analysed in terms of bitrate, image quality, memory size and energy consumption. Experiments are carried out with Atmel ATmega128 processor. The experimental results show that this system consumes only 0.23% of energy consumed by true Discrete Cosine Transform-based Joint Photographic Experts Group (JPEG) standard and offers reasonable image quality suitable for visual perception at low bitrate. This system requires only 19% of memory required by standard JPEG.     

三维医学图像优化压缩算法

针对 CT 三维医学图像特点,将三维医学数据分块,通过平滑处理和边界交迭减小分块失真,将 SPIHT 算法与 SPECK 算法结合,帧内采用 SPIHT 算法,帧间利用 SPECK 编码算法,组合算法提高了压缩效率,优于单一的算法。     

Numerical integration schemes for the BEM solution of hypersingular integral equations

In this paper we consider singular and hypersingular integral equations associated with 2D boundary value problems defined on domains whose boundaries have piecewise smooth parametric representations. In particular, given any (polynomial) local basis, we show how to compute efficiently all integrals required by the Galerkin method. The proposed numerical schemes require the user to specify only the local polynomial degrees; therefore they are quite suitable for the construction of p‐ and h‐p versions of Galerkin BEM. Copyright © 1999 John Wiley & Sons, Ltd.     

带噪图像的多阈值零树编码方法

零树编码利用一固定量化阈值对系数进行扫描,而多阈值零树编码将小波分解后各子带的最大系数作为该子带的扫描阈值,将扫描阈值大于量化阈值的子带作为重要子带,反之作为次要子带。只在重要子带中判断其是否存在重要系数。针对含有高斯白噪声的图像,引入混合降噪模型对各子带的扫描阈值进行修正,有效地提高了编码图像质量和编码效率。     

Digital watermarking based on fractal image coding

Abstract

With advances in computer network and multimedia technology, digital media are rapidly proliferating, and thus the issue of copyright protection for electronic publishing is receiving great attention. To achieve the goal of copyright protection, the digital watermarks are used to identify the owner of a certain image, so as to prevent illegal copying. Digital watermarking is the technique that embeds an invisible signal including owner identification and copy control information into multimedia data such as audio, video, and images. A new digital watermark approach based on fractal image coding is proposed in this paper. We present a way to use the fractal code as a means of embedding a watermark into image. The proposed approach has been shown to be resistant to general attacks, like StirMark. Moreover, someone who owns the decryption key can simply extract the digital watermark from the watermarked image without resorting to the original image.     

一种利用离散余弦变换频谱图和小波变换图像编码的语音编码算法

语音、图像编码技术是现代数字通信的核心技术,通常是分开进行的,提出了一种利用二维DCT频谱图和小波变换图像编码的语音编码算法.深入分析了算法实现的关键技术——语音信号的二维DCT频谱图,仿真实现了该编码算法,对一段语音的处理结果表明,小波分解系数置零率为83.1941％,压缩后保存能量92.0867％,合成语音达到“优...     

Generalized quantization as an effective image coding method

Several methods of generalized image quantization, being an ?-network reduction with the use of visual perception limits, are discussed. The corresponding digital image transformations provide an effective image coding with the following image transmission through communication channels and its storage in the database.     

Finite state residual vector quantizer for image coding

Finite state vector quantization (FSVQ) has been proven to be a high-quality and low-bit rate coding scheme. An FSVQ has achieved the efficiency of a small codebook (the state codebook) VQ while maintaining the quality of a large codebook (the master codebook) VQ. However, the large master codebook becomes a primary limitation of FSVQ when the implementation is carefully taken into account. A large amount of memory would be required in storing the master codebook, and much effort would be spent in maintaining the state codebook if the master codebook became too large. This problem could be partially solved by the mean/residual technique (MRVQ)-that is, the block means and the residual vectors would be separately coded. However, MRVQ has its own drawbacks. Additional bits would be required in coding those means. Moreover, electing the state codebooks in the residual domain would be difficult. A new hybrid coding scheme called the finite state residual vector quantization (FSRVQ) is proposed in this article for the sake of using both advantage in FSVQ and MRVQ. The codewords in FSRVQ were designed by removing the block means to reduce the codebook size. The block means were predicted by the neighboring blocks to reduce the bit rate. In addition, the predicted means were added to the residual vectors so that the state codebooks could be generated entirely. The performance of FSRVQ was indicated from the experimental results to be better than that of both ordinary FSVQ and MRVQ uniformly.©1994 John Wiley & Sons Inc     

Colour image coding scheme using absolute moment block truncation coding and block prediction technique

Abstract

A predictive colour image compression scheme based on absolute moment block truncation coding is proposed. In this scheme, the high correlations among neighbouring image blocks are exploited by using the similar block prediction technique. In addition, the bit plane omission technique and the coding of quantisation levels are used to cut down the storage cost of smooth blocks and complex blocks respectively. According to the experimental results, the proposed scheme provides better performance than the comparative schemes based on block truncation coding. It provides better image qualities of compressed images at low bit rates. Meanwhile, it consumes very little computational cost. In other words, the proposed scheme is quite suitable for real time multimedia applications.     

Boundary integral equations and conservative dissipation schemes for full potential transonic flows

A boundary integral formulation for the nonlinear aerodynamic analysis of three-dimensional full-potential transonic flows is presented. The emphasis here is on the analysis of the effects on the solution of artificial dissipation schemes, which are necessary in order to capture properly the physics of the phenomenon. The main novelty is the use of conservative schemes, never previously used in boundary integral formulations where all the existing approaches are based on non-conservative ones. The conservative scheme presented here is an adaptation of concepts used in the CFD community. Specifically, a linear dissipation term is added directly to the continuity equation: hence the name artificial mass-generation scheme. Both conservative and non-conservative full-potential expressions for the nonlinear terms are discussed. The corresponding TSP (transonic small perturbation) formulation are also analyzed. Numerical results, for two-dimensional steady flows are presented in order to assess the different schemes. Good agreement is obtained with existing finite-difference and finite-volume results.     

Hierarchical prediction structure for subimage coding and multithreaded parallel implementation in integral imaging

We are concerned with the coding of subimage-transformed elemental images to solve the problems of data transmission and storage in three-dimensional (3D) integral imaging in this paper. First, we use the subimage transform for preprocessing of the elemental image array (EIA). Because of the similarity of correlation distributions between the subimage array (SIA) and multiview video, we present a hierarchical prediction structure for SIA coding based on the hierarchical B picture (HBP) structure for multiview video coding. Moreover, we design a multithreaded parallel implementation for the proposed structure according to inter-row prediction dependencies. Experiments are performed on both EIAs and SIAs. The results show that employing the same coding strategy, the proposed parallel implemented HBP scheme achieves not only higher image quality and better 3D effect but also lower coding delay at low bit rates compared with the previously reported Hilbert-curve-based scheme.     

General derivative approximations for finite different schemes

A general expression for finite difference approximations for all derivatives up to the (N ? 1)th order on a finite difference mesh with N-nodes is established. The mesh may be non-uniform and the derivative evaluated at any of the N-nodes. An estimate for the truncation error is obtained and shown to depend on the nonlinearity of the mesh as well as on the mesh diameter. Specific formulae for first- and second-order derivatives are given as examples.     

Right-cyclic Hadamard coding schemes and fast Fourier transformsfor use in computing spectrum estimates in Hadamard-transformspectrometry

Two computationally efficient spectrum-recovery schemes were recently developed for use by Hadamard-transform spectrometers that have static and dynamic nonidealities in their encoding masks. These methods make use of a left-cyclic Hadamard encodement scheme and the ability to express the left-cyclic W_D matrix in factored form as W_D =ST_D. The matrix W_D describes the dynamic characteristics of and the encodement scheme for the mask. This paper focuses on the use of a right-cyclic Hadamard pattern to encode the mask and computationally efficient methods that can be used to obtain the spectrum-estimate. The major advantage of right-cyclic over left-cyclic encodement schemes is due to the resulting right-cyclic nature of both W _D and W_D^-1. Fast algorithms, such as a fast Fourier transform (FFT) or a Trench algorithm, that take advantage of the right-cyclic nature of W_D can be used to obtain W_D^-1 directly. In general, the number of mask elements is not an integer power of two, and non-radix-2 FFT's must be used to compute W_D^-1. Since W_D^-1 is right-cyclic, the vector-matrix product of W_D^-1 and the measurement vector can be expressed as a circular correlation and implemented indirectly via FFT's. With appropriate zero-padding of the vectors, radix-2 FFT's can be used for this computation. Various algorithms were used at each step in the overall computation of the spectrum-estimate, and the total computation times are presented and compared. The size of the mask is important in determining which algorithms are the most efficient in recovering the spectrum-estimate     

Three-dimensional complex image coding using a circular Dammann grating

Recently, optical image coding using a circular Dammann grating (CDG) has been proposed and investigated. However, the proposed technique is intensity based and could not be used for three-dimensional (3D) image coding. In this paper, we investigate an optical image coding technique that is complex-amplitude based. The system can be used for 3D image coding. The complex-amplitude coding is provided by a circular Dammann grating through the use of a digital holographic recording technique called optical scanning holography. To decode the image, along the depth we record a series of pinhole holograms coded by the CDG. The decoded reconstruction of each depth location is extracted by the measured pinhole hologram matched to the desired depth. Computer simulations as well as experimental results are provided.     

二值图像中的游程编码区域标记

由于处理时间及存储空间的限制,常规的区域标记算法往往无法满足实时图像处理的需要。针对这些不足,提出了一种新的快速区域标记算法。通过改变游程编码的存储结构,建立编码间的亲缘关系,实现快速地址寻访,完成二值图像中所有区域目标对象的标记过程。与传统的标记算法相比,降低了算法复杂度,缩短了处理时间。     

Classified variable-block-size motion estimation algorithm for image sequence coding

In recent years, the variable-block-size (VBS) motion estimation technique has been widely employed to improve the performance of the block-matching algorithm (BMA). In VBS, the block size is varied according to the type of motion. The VBS is known to be very efficient for areas containing complex motions. However, it requires a large number of computations. In this article, a new VBS motion estimation algorithm, called the classified variable block size (CVBS), is proposed to overcome this problem. The algorithm classifies the input blocks into three categories: background, shade motion and edge motion. According to the characteristics of the classified blocks, various motion estimation techniques are then used to improve the coding performance. The performance of VBS and CVBS based on the coding efficiency is investigated. It is shown that the CVBS algorithm requires about one fifth to one seventh of the computations needed by the conventional VBS algorithm. © 1996 John Wiley & Sons, Inc.     

Projection-type integral imaging system using multiple elemental image layers

A projection-type integral imaging system is proposed using multiple elemental image layers obtained from a single projector. In a conventional projection-type integral imaging system, only one display mode among real, virtual, and focused modes can be displayed selectively with a single projector. Plural projectors must be used for the generation of multiple elemental image layers. However, in the proposed method, the real and the virtual modes can be displayed simultaneously by generating multiple elemental image layers within the depth of field of a single projector. To embody the proposed method, the system specifications, such as the focal lengths of lenses and the distance between components, must be designed carefully. In this paper, we define and calculate the system factors and present the design role of the system. The feasibility of the proposed method is demonstrated with experimental results.