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International conference on Computational Intelligence and Multimedia applications

作者： G. Sreelekha P.S. Sathidevi Department of Electronics Engineering National Institute of Technology Calicut Kerala India

ISBN: (纸本)9780769530505;0769530508

A perceptual image coder for the compression of monochrome images is presented here, in which the coding structure is coupled with a vision model to produce coded images with an improved visual quality at low bit-rates. The coder is an improvement on the current image compression standard, JPEG2000. The proposed coding structure incorporates the human vision model in all stages of compression, and gives very good results compared to the existing wavelet based JPEG scheme. Though the mathematical model used are not new, the simple structure of it which can be easily incorporated into the coding structure of the JPEG2000, incorporates the visual processing stages in a very systematic manner in the same way as the visual neurons process the signal. The results presented in this paper reveal that the proposed structure gives very good perceptual quality compared to the existing scheme especially as we go for lower bit rates. One of the major advantages of the proposed scheme is that it can be easily extended to a structure in which the rate control optimization can be incorporated, as in the JPEG2000.

关键词： Humans Visual system image coding Transform coding Optical distortion Optical sensors Discrete wavelet transforms Machine vision Quantization Frequency

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An Efficient Implementation of a 2D DWT on FPGA

An Efficient Implementation of a 2D DWT on FPGA

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International conference on Field Programmable Logic and applications

作者： Michael Wisdom Peter Lee Electronics Department University of Kent UK

This paper presents a high-speed implementation of a 2-D fixed-point discrete wavelet transform (DWT) using the embedded DSP48 blocks available on a Xilinx Virtex-4 XC4VLX15-10 FPGA. The full transform uses just 10 DSP48 blocks, 3 block RAMs and 2,126 logic elements when synthesized using Xilinx ISE Version 8.2i and can perform calculations at 197.2 MHz. The results clearly show that by using the DSP48 blocks, it is possible to build computationally efficient DWT algorithms that can operate at higher speeds and with lower overall logic resources than other FPGA solutions that have been reported previously.

关键词： Discrete wavelet transforms Field programmable gate arrays Hardware Low pass filters image coding Logic signal processing algorithms Digital signal processing Finite impulse response filter Computer architecture

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Very Lowbit Rate ideo Codec Based on Diffrentialwavelet Filters

Very Lowbit Rate ideo Codec Based on Diffrentialwavelet Filt...

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International conference on Computational Science and its applications (ICCSA)

作者： Mostafa A. Ahmad Ayoub Al-Hamadi Gerald Krell B. Michaelis Signal Processing and Communications Otto-von-Guericke University Magdeburg Magdeburg Germany

State-of-the-art in digital coding/decoding includes discrete image transformation, quantization, and entropy coding. The key to efficient data compression is associated with image transformation/reconstruction processes. In this paper, we present a different filters wavelet-based intra-frame video coding technique. The wavelet transformation is developed and optimized in order to enhance the visual quality especially at very low bit rate. The proposed coding technique reduces the bit rate while performing well regarding PSNR and visual quality. In comparison with the conventional coding methods, our proposed coding technique provides significant performance gains in objective and subjective quality.

关键词： Codecs Filters Bit rate image coding Decoding Quantization Entropy coding Data compression image reconstruction Video coding

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A Rate-Constrained Pre-Compression Bit Allocation Algorithm for Memory Constrained Embedded applications of JPEG2000

A Rate-Constrained Pre-Compression Bit Allocation Algorithm ...

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IEEE International conference on signal processing and Communications, ICSPC

作者： Alireza Aminlou Amir Naghdinezhad Mahmoud Reza Hashemi Omid Fatemi Multimedia Processing Laboratory School of Electrical and Computer Engineering University of Tehran Tehran Iran

The execution order of the main components in a JPEG2000 encoder, i.e. the coding sequence, plays a significant role in its performance, implementation cost and memory requirement. The coding sequence is mainly affected by the bit allocation strategy. Existing strategies either require a large working memory or can not be used in rate constrained applications. In this paper, an improved pre-compression bit allocation algorithm for rate-constrained applications of JPEG2000 is proposed. Using the proposed method with multi-layered coding, the memory requirement of a JPEG2000 system is reduced by more than 80%. This is at the expense of a quality degradation of merely 0.47 dB in average, for higher compression ratios of 50 to 100.

关键词： Bit rate image coding Discrete wavelet transforms signal processing algorithms Transform coding Video coding Rate distortion theory Application software Laboratories Embedded computing

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Oversampled Inverse Complex Lapped Transform Optimization

Oversampled Inverse Complex Lapped Transform Optimization

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International conference on Acoustics, Speech, and signal processing (ICASSP)

作者： Jerome Gauthier Laurent Duval Jean-Christophe Pesquet Institut Français du Pétrole IFP Rueil-Malmaison Cedex France Institut Gaspard Monge and UMR CNRS 8049 Université de Marne La Vallée Marne La Vallée

When an oversampled FIR filter bank structure is used for signal analysis, a main problem is to guarantee its invertibility and to be able to determine an inverse synthesis filter bank. As the analysis scheme corresponds to a redundant decomposition, there is no unique inverse filter bank and some of the solutions can lead to artifacts in textured image filtering applications. In this paper, the flexibility in the choice of the inverse filter bank is exploited to find the best-localized impulse responses. The design is performed by solving a constrained optimization problem which is reformulated in a smaller dimensional space. Application to seismic data clearly shows the improvements brought by the optimization process.

关键词： Finite impulse response filter Filter bank Filtering Discrete cosine transforms signal analysis signal synthesis Design optimization wavelet transforms image analysis image texture analysis

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wavelets: a Versatile Tool for the High Frequency Surface Wave Radar

Wavelets: a Versatile Tool for the High Frequency Surface Wa...

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IEEE National conference on Radar

作者： Florent Jangal Stephane Saillant Marc Helier Office National d'Etudes et de Recherches Aérospatiales The French Aerospace Laboratory Palaiseau France Université Pierre et Marie Curie Ivry-sur-Seine France

Widely used in image processing, wavelets seem to be a promising versatile tool for the high frequency surface wave radar (HFSWR). HFSWR is based on the ability of HF waves (3 MHz to 30 MHz) to propagate along the earth curvature. HFSWR can detect targets up to few hundred kilometers beyond the horizon. The two main applications of the HFSWR are the maritime surveillance of the exclusive economic zone (EEZ) and the remote sensing of the sea. Beside the classical noise which affects all radar signals, the detection capabilities of HFSWR suffer from two limitations: the sea clutter and the ionospheric clutter which are target masks. However sea clutter can be used to perform remote sensing of the sea. In this paper we are studying how wavelets may contribute to the improvement of radar signal processing. We consider general de-noising feature for radar signals, we carry out a wavelet-based improvement of remote sensing of oceanographic parameters and we show the first results of a wavelet-based processing for ionospheric clutter mitigation.

关键词： Frequency Surface waves Remote sensing Sea surface Radar imaging Radar detection Radar clutter Radar remote sensing Radar signal processing image processing

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Colour Volumetric Compression for Realistic View Synthesis applications

Colour Volumetric Compression for Realistic View Synthesis A...

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International conference on Acoustics, Speech, and signal processing (ICASSP)

作者： N. Anantrasirichai C. Nishan Canagarajah David W. Redmill David R. Bull Department of Electrical & Electronic Engineering University of Bristol Bristol UK

The colour volumetric data which is constructed from a set of multi-view images is capable of providing realistic immersive experience. However it is not widely applicable due to its manifold increase in bandwidth. This paper presents a novel framework to achieve scalable volumetric compression. Based on wavelet transformation, data rearrangement algorithm is proposed to compact volumetric data leading to high efficiency of transformation. The colour data is also rearranged by using the characteristics of human eye sensitivity. Moreover, the pre-processing for adaptive resolution is proposed in this paper. The low resolution overcomes the limitation of the data transmission at low bit rate, whilst the fine resolution improves the synthesised images' quality. The results of our proposed schemes show significant improvement of the compression performance over the traditional 3D coding.

关键词： image coding Bit rate Bandwidth Humans image resolution Data communication Medical services Biomedical equipment Data engineering Manifolds

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Motion-compensated orthogonal transforms for multiview video coding

Motion-compensated orthogonal transforms for multiview video...

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European signal processing conference (EUSIPCO)

作者： Markus Flierl Max Planck Center for Visual Computing and Communication Stanford University California

This paper discusses coding of multiview video with motion-compensated orthogonal transforms. These transforms have recently been introduced to generate strictly orthonormal decompositions of image sequences. Orthonormality is maintained for arbitrary motion compensation among the images. This is of particular interest for coding applications as motion compensation is inaccurate due to quantization of motion information. This is in contrast to the well known motion-compensated lifted wavelets where the properties of the decomposition are motion-dependent. This disadvantage affects compression efficiency and in particular that of multiview video signals. Multiview video coding schemes utilize motion and disparity compensation when decomposing the multiview imagery into view-temporal subbands. Usually decompositions in time and view direction are cascaded. Motion-compensated lifted wavelets suffer from their motion-dependent decomposition and in particular if cascaded for multiview video coding. On the other hand motion and disparity compensated orthogonal transforms offer the advantage that the overall decomposition is still strictly orthonormal. This paper investigates the advantages of strict orthonormality that is offered by motion-compensated orthogonal transforms.

关键词： Video coding Encoding Motion compensation wavelet transforms Radiation detectors image sequences

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Implementation of noise reduction for PET using hybrid nonlinear wavelet shrinkage method

Implementation of noise reduction for PET using hybrid nonli...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： Akihiro Ishikawa Keishi Kitamura Tetsuro Mizuta Kazumi Tanaka Masaharu Amano Yoshihiro Inoue Medical Systems Division Shimadzu Corporation Kyoto Japan Shimadzu Corporation Japan

Positron emission tomography (PET) imaging provides the functional information and precise physiological uptake of radioactivity in a patient's body. But the photon level of PET system has fewer level, the shortcoming of PET is low SNR. The quantum noise in emission data can have a significant influence on the statistical uncertainty of PET measurements. The reduction of the quantum noise in images is an important issue. Conventional post-processing is not completely suitable, since it leads to loss of the spatial resolution while reducing noise. In this study, we present a method for denoising the quantum noise in images. Our proposed methods is to use a hybrid wavelet shrinkage processing in 3D sinogram(bin,angle,slice) domain. One is applied to axial(bin,angle) space to reduce detector dependence noise element, the other is applied to 3D space to reduce quantum noise. We optimized three parameters in each wavelet processing. The efficacy of the filtering technique was shown on a derenzo phantom. Finally, we also performed human FDG studies to evaluate clinical performance. As result, we have found that the optimized parameters and reconstructed image without post filtering in proposed study reduce COV while maintaining average and spatial resolution. We therefore conclude that wavelet de-noising technique is an effective tool to process PET images and thus to provide better image quality. We expect that our study can provide benefits to clinical applications of PET images.

关键词： Noise reduction Positron emission tomography Spatial resolution Filtering signal to noise ratio Measurement uncertainty Noise measurement wavelet domain Detectors Imaging phantoms

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wavelet-based pavement distress detection and evaluation

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OPTICAL ENGINEERING 2006年第2期45卷

作者： Zhou, J Huang, PS Chiang, FP SUNY Stony Brook Dept Mech Engn Stony Brook NY 11794 USA

An automated pavement inspection system consists of image acquisition and distress image processing. The former is accomplished with imaging sensors, such as video cameras and photomultiplier tubes. The latter includes distress detection, isolation, classification, evaluation, segmentation, and compression. We focus on wavelet-based distress detection, isolation, and evaluation. After a pavement image is decomposed into different-frequency subbands by the wavelet transform, distresses are transformed into high-amplitude wavelet coefficients and noise is transformed into low-amplitude wavelet coefficients, both in the high-frequency subbands, referred to as details. Background is transformed into wavelet coefficients in a low-frequency subband, referred to as approximation. First, several statistical criteria are developed for distress detection and isolation, which include the high-amplitude wavelet coefficient percentage (HAWCP), the high-frequency energy percentage (HFEP), and the standard deviation (STD). These criteria are tested on hundreds of pavement images differing by type, severity, and extent of distress. Experimental results demonstrate that the proposed criteria are reliable for distress detection and isolation and that real-time distress detection and screening is currently feasible. A norm for pavement distress quantification, which is defined as the product of HAWCP and HFEP, is also proposed. Experimental results show that the norm is a useful index for pavement distress evaluation. (c) 2006 Society of Photo-Optical Instrumentation Engineers.

关键词： wavelet transform automated pavement inspection pavement distress image processing distress detection and isolation distress evaluation

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