With the tremendous increase in the capabilities of wireless multimedia devices and services, the demand to improve quality of such systems within the limited bandwidth resources motivates the interest in robust video...
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ISBN:
(纸本)300018726X
With the tremendous increase in the capabilities of wireless multimedia devices and services, the demand to improve quality of such systems within the limited bandwidth resources motivates the interest in robust video transmission. In the paper, a new unequal error protect (UEP) scheme is proposed for robust wireless video transmission by using LDPC codes and data partitioning. Considering bandwidth limitation of wireless video applications, our proposed algorithm features assigning an unequal number of forward error correction (FEC) bits to each data partition for H.264, thus efficiently makes use of limited available resources. Simulation results demonstrate that the proposed algorithm is more robust compared with those obtained with equal error protect (EEP) technique and common coding mode, such as Turbo codes.
An adaptive blind wavelet-based watermarking scheme using tree mutual differences (ABW-TMD) is proposed by exploiting mutual differences between grouped coefficients of so-called wavelet trees. The ABW-TMD encoder ada...
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An adaptive blind wavelet-based watermarking scheme using tree mutual differences (ABW-TMD) is proposed by exploiting mutual differences between grouped coefficients of so-called wavelet trees. The ABW-TMD encoder adaptively searches for the bit host difference in such a manner to minimize the embedding error The proposed ABW-TMD scheme proves its superiority in resisting against various imageprocessing attacks as well as in reducing the computational cost when compared to other schemes. For the same watermark bit length, a 35% increase in peak signal-to-noise ratio (PSNR) can be achieved over what is possible using an earlier method. Also, when fixing the PSNR of the watermarked image, the watermark bit length can be doubled with the ability to extract the watermark, even in the presence of high JPEG/JPEG2000 compression ratios. (c) 2006 SPIE and IS&T.
The 1990s witnessed an explosion of wavelet-based methods in the field of imageprocessing. This article will focus primarily on wavelet-based image compression. We shall describe the connection between wavelets and v...
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Probabilistic arithmetic, where the ith output bit of addition and multiplication is correct with a probability pi, is shown to be a vehicle for realizing extremely energy-efficient, embedded computing. Specifically, ...
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ISBN:
(纸本)1595935436
Probabilistic arithmetic, where the ith output bit of addition and multiplication is correct with a probability pi, is shown to be a vehicle for realizing extremely energy-efficient, embedded computing. Specifically, probabilistic adders and multipliers, realized using elements such as gates that are in turn probabilistic, are shown to form a natural basis for primitives in the signalprocessing (dsp) domain. In this paper, we show that probabilistic arithmetic can be used to compute the fft in an extremely energy-efficient manner, yielding energy savings of over 5.6x in the context of the widely used synthetic aperture radar (sar) application [1]. Our results are derived using novel probabilistic cmos (pcmos) technology, characterized and applied in the past to realize ultra-efficient architectures for probabilistic applications [2, 3, 4]. When applied to the dsp domain, the resulting error in the output of a probabilistic arithmetic primitive, such as an adder for example, manifests as degradation in the signal-to-noise ratio (snr) of the sar image that is reconstructed through the fft algorithm. In return for this degradation that is enabled by our probabilistic arithmetic primitives - degradation visually indistinguishable from an image reconstructed using conventional deterministic approaches-significant energy savings and performance gains are shown to be possible per unit of snr degradation. These savings stem from a novel method of voltage scaling, which we refer to as biased voltage scaling (or bivos), that is the major technical innovation on which our probabilistic designs are based. Copyright 2006 ACM.
The dual-tree complex wavelet (DT CWT) was introduced to overcome the disadvantages of the traditional fully decimated discrete wavelet transform (DWT), namely the shift-variance and the poor directional selectivity. ...
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The dual-tree complex wavelet (DT CWT) was introduced to overcome the disadvantages of the traditional fully decimated discrete wavelet transform (DWT), namely the shift-variance and the poor directional selectivity. Because of its desirable properties, the dual-tree has been successful in many imageprocessingapplications. However, its use in data compression has been hindered because of its redundancy. Our goal is to be able to predict the wavelet coefficients of one tree knowing those of the other tree. The proposed method is based on exploiting the orthogonality properties of one of the nicest dual-tree designs, the Q-shift complexwavelets.
Designing embedded systems is a challenging task during which wrong choices can lead to extremely costly re-design loops, especially when these wrong choices are made during the algorithm specification and the mapping...
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Designing embedded systems is a challenging task during which wrong choices can lead to extremely costly re-design loops, especially when these wrong choices are made during the algorithm specification and the mapping over the selected architecture. In this paper we propose a high-level approach for design space exploration, using a usual standard language as input. More precisely we present the two first steps of the Design Trotter framework: (i) the specification step and its underlying internal model (HCDFG: Hierarchical and Control Data Flow Graph) and (ii) the characterization step which takes place very early in the design flow. Indeed, once transformed into our internal representation, the specification is rapidly and automatically characterized and explored at the algorithmic level. The framework provides the designer with metrics so that he can evaluate, very early in the design process, the impact of algorithmic choices on resource requirements in terms of processing, control, memory bandwidth and potential parallelism at different levels of granularity. The overall aim of our approach is to improve the algorithm/architecture matching that sorely influences the implementation efficiency in terms of silicon area, performances and energy consumption. We give examples which illustrate how designers can refer to the outcomes of the Design Trotter framework in order to select or build suitable architectures for specific applications.
In this paper, we present an optimized design method for high-speed embedded imageprocessing system using 32 bit floating-point Digital signal Processor (DSP) and Complex Programmable Logic Device (CPLD). The DSP act...
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In this paper, we present an optimized design method for high-speed embedded imageprocessing system using 32 bit floating-point Digital signal Processor (DSP) and Complex Programmable Logic Device (CPLD). The DSP acts as the main processor of the system: executes digital imageprocessing algorithms and operates other devices such as image sensor and CPLD. The CPLD is used to acquire images and achieve complex logic control of the whole system. Some key technologies are introduced to enhance the performance of our system. In particular, the use of DSP/BIOS tool to develop DSP applications makes our program run much more efficiently. As a result, this system can provide an excellent computing platform not only for executing compleximageprocessing algorithms, but also for other digital signalprocessing or multi-channel data collection by choosing different sensors or Analog-to-Digital (A/D) converters.
This dissertation describes magnetic resonance imaging (MRI) of protons performed in a precession field of 132 μT. In order to increase the signal-to-noise ratio (SNR), a pulsed 40-300 mT magnetic field prepolarizes ...
This dissertation describes magnetic resonance imaging (MRI) of protons performed in a precession field of 132 μT. In order to increase the signal-to-noise ratio (SNR), a pulsed 40-300 mT magnetic field prepolarizes the sample spins and an untuned second-order superconducting gradiometer coupled to a low transition temperature superconducting quantum interference device (SQUID) detects the subsequent 5.6-kHz spin precession. Imaging sequences including multiple echoes and partial Fourier reconstruction are developed. Calculating the SNR of prepolarized SQUID-detected MRI shows that three-dimensional Fourier imaging yields higher SNR than slice-selection imaging. An experimentally demonstrated field-cycling pulse sequence and post-processing algorithm mitigate image artifacts caused by concomitant gradients in low-field MRI. The magnetic field noise of SQUID untuned detection is compared to the noise of SQUID tuned detection, conventional Faraday detection, and the Nyquist noise generated by conducting biological samples. A second-generation microtesla MRI system employing a low-noise SQUID is constructed to increase SNR. A 2.4-m cubic, eddy-current shield with 6-mm thick aluminum walls encloses the experiment to attenuate external noise. The measured noise is 0.75 fT Hz 1/2 referred to the bottom gradiometer loop. Solenoids wound from 30-strand braided wire to decrease Nyquist noise and cooled by either liquid nitrogen or water polarize the spins. Copper wire coils wound on wooden supports produce the imaging magnetic fields and field gradients. Water phantom images with 0.8 x 0.8 x 10 mm3 resolution have a SNR of 6. Three-dimensional 1.6 x 1.9 x 14 mm3 images of bell peppers and 3 x 3 x 26 mm3 in vivo images of the human arm are presented. Since contrast based on the transverse spin relaxation rate (T1 ) is enhanced at low magnetic fields, microtesla MRI could potentially be used for tumor imaging. The measured T1 of ex vivo normal and cancerous prostate tissue dif
applications for video data recorded with a setup of several cameras are currently attracting increasing interest. For such multi-view sequences, efficient coding is crucial to handle the enormous amount of data. Howe...
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ISBN:
(纸本)300018726X
applications for video data recorded with a setup of several cameras are currently attracting increasing interest. For such multi-view sequences, efficient coding is crucial to handle the enormous amount of data. However, significant luminance and chrominance variations between the different views, which often originate from imperfect camera calibration, are able to reduce the coding efficiency and the rendering quality. In this paper, we suggest the usage of histogram matching to compensate these differences in a pre-filtering step. After a description of the proposed algorithm, it is explained how histogram matching can be applied to multi-view video data. The effect of histogram matching on the coding performance is evaluated by statistically analysing prediction from temporal as well as from spatial references. For several test sequences, results are shown which indicate that the amount of spatial prediction across different camera views can be increased by applying histogram matching.
A novel face detection algorithm is presented by applying dual tree complexwavelets transform (DT-CWT) on spectral histogram PCA space (SHPCA) and support vector machine (SVM). DT-CWT is a transform recently studied,...
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A novel face detection algorithm is presented by applying dual tree complexwavelets transform (DT-CWT) on spectral histogram PCA space (SHPCA) and support vector machine (SVM). DT-CWT is a transform recently studied, which provides good directional selectivity in six different fixed orientations at different scales. It has limited redundancy for images and is much faster than Gabor transform to compute. Hence, DT-CWT is a good choice to replace Gabor transform in some imagesignals processing fields especially for face images representation. In the face detection algorithm presented in this paper, images are first projected to SHPCA space after convolved with different filters including DT-CWT filters to achieve features subtraction based on frequency. Then on SHPCA space SVM classification is applied to detect whether faces exist in images or not. The experimental results show that DT-CWT performs much better than Gabor transform on SHPCA space. Furthermore, during preliminary experiments, SVM based on SHPCA space has been trained on a training set of 4000 faces aligned and 6000 non-face images, and a robust classifying function for face and non-face pattern is obtained, which gives the satisfying performance. Several questions about computation time saving and performance improvement are discussed
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