This paper proposes a novel functionality in wavelet-based irregular mesh coding, which is interactive region-of-interest (ROI) support. The proposed approach enables the user to define the arbitrary ROIs at the decod...
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This paper proposes a novel functionality in wavelet-based irregular mesh coding, which is interactive region-of-interest (ROI) support. The proposed approach enables the user to define the arbitrary ROIs at the decoder side and to prioritize and decode these regions at arbitrarily high-granularity levels. In this context, a novel adaptive wavelet transform for irregular meshes is proposed, which enables: 1) varying the resolution across the surface at arbitrarily fine-granularity levels and 2) dynamic tiling, which adapts the tile sizes to the local sampling densities at each resolution level. The proposed tiling approach enables a rate-distortion-optimal distribution of rate across spatial regions. When limiting the highest resolution ROI to the visible regions, the fine granularity of the proposed adaptive wavelet transform reduces the required amount of graphics memory by up to 50%. Furthermore, the required graphics memory for an arbitrary small ROI becomes negligible compared to rendering without ROI support, independent of any tiling decisions. Random access is provided by a novel dynamic tiling approach, which proves to be particularly beneficial for large models of over 10(6) similar to 10(7) vertices. The experiments show that the dynamic tiling introduces a limited lossless rate penalty compared to an equivalent codec without ROI support. Additionally, rate savings up to 85% are observed while decoding ROIs of tens of thousands of vertices.
Wireless control systems can sense, control and act on the information exchanged between the wireless sensor nodes in a control loop. However, the exchanged information becomes susceptible to the degenerative effects ...
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Wireless control systems can sense, control and act on the information exchanged between the wireless sensor nodes in a control loop. However, the exchanged information becomes susceptible to the degenerative effects produced by the multipath propagation. In order to minimize the destructive effects characteristic of wireless channels, several techniques have been investigated recently. Among them, wavelet coding is a good alternative for wireless communications for its robustness to the effects of multipath and its low computational complexity. This work proposes an adaptive wavelet coding whose parameters of code rate and signal constellation can vary according to the fading level and evaluates the use of this transmission system in a control loop implemented by wireless sensor nodes. The performance of the adaptive system was evaluated in terms of bit error rate (BER) versus E-b/N-0 and spectral efficiency, considering a time-varying channel with flat Rayleigh fading, and in terms of processing overhead on a control system with wireless communication. The results obtained through computational simulations and experimental tests show performance gains obtained by insertion of the adaptive wavelet coding in a control loop with nodes interconnected by wireless link. These results enable the use of this technique in a wireless link control loop.
The advance in wireless sensor networking technology is increasing the number of control systems that use these networks to transmit the relevant variable to be measured and controlled, despite of the more intense dis...
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ISBN:
(纸本)9781509033027
The advance in wireless sensor networking technology is increasing the number of control systems that use these networks to transmit the relevant variable to be measured and controlled, despite of the more intense distortions caused by wireless channels. The performance of wireless communications systems is mainly limited by fading produced by multipath propagation. In order to minimize the fading effects, channel coding and diversity techniques are often used in wireless systems. Among the known coding techniques in the literature, the wavelet coding presents an interesting alternative to overcome the multipath fading, since it gets performance gain by transmitting in time diversity without compromising spectral efficiency. This paper investigates the use of wavelet coding in a system that operates over a wireless channel to control the rotation frequency of the direct current motor. Aspects such as packet error probability performance, hardware complexity and processing delays due to wavelet coding are analyzed, as well as its beneficial effects on the control system. In the proposed system, the wavelet coding was embedded in PIC microcontroller and a radio transceiver XBee is used to establish a wireless link. The obtained results demonstrate a reduction of fading effects on the control signal, as well as, a low cost for hardware implementation and a small impact on system processing time.
The paper presents the results of estimating image distortions inherent for compression algorithms based on the complex implementation of wavelet coding taking into account the tradeoff between the degree of compressi...
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ISBN:
(纸本)9781538624685
The paper presents the results of estimating image distortions inherent for compression algorithms based on the complex implementation of wavelet coding taking into account the tradeoff between the degree of compression and the transmission of texture. Estimations of the level of distortion of image contours are given depending on the detail and texture characteristics on large areas of the image with a smooth brightness variation. The choice of test images containing low-contrast textures with different levels of medium brightness is justified. As a measure of the distortion between the original and the decoded image, the ratio of the peak value of the signal to the average noise value at the boundary of the contours of objects in the image is selected. The boundaries were detected by a gradient method. Compression factors are calculated for varying the thresholds of the restriction of the spectral components at different levels of the wavelet decomposition. A variant of the frequency-dependent restriction of the spectral components is proposed, which is determined for each of the sub-bands. Appropriate values of the compression ratio for the coding method based on the prediction of bit planes for a given set of images are presented.
Especially in lossless image coding the obtainable compression ratio strongly depends on the amount of noise included in the data as all noise has to be coded, too. Different approaches exist for lossless image coding...
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ISBN:
(纸本)9781457720482
Especially in lossless image coding the obtainable compression ratio strongly depends on the amount of noise included in the data as all noise has to be coded, too. Different approaches exist for lossless image coding. We analyze the compression performance of three kinds of approaches, namely direct entropy, predictive and wavelet-based coding. The results from our theoretical model are compared to simulated results from standard algorithms that base on the three approaches. As long as no clipping occurs with increasing noise more bits are needed for lossless compression. We will show that for very noisy signals it is more advantageous to directly use an entropy coder without advanced preprocessing steps.
The paper presents the results of estimating image distortions inherent for compression algorithms based on the complex implementation of wavelet coding taking into account the tradeoff between the degree of compressi...
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The paper presents the results of estimating image distortions inherent for compression algorithms based on the complex implementation of wavelet coding taking into account the tradeoff between the degree of compression and the transmission of texture. Estimations of the level of distortion of image contours are given depending on the detail and texture characteristics on large areas of the image with a smooth brightness variation. The choice of test images containing low-contrast textures with different levels of medium brightness is justified. As a measure of the distortion between the original and the decoded image, the ratio of the peak value of the signal to the average noise value at the boundary of the contours of objects in the image is selected. The boundaries were detected by a gradient method. Compression factors are calculated for varying the thresholds of the restriction of the spectral components at different levels of the wavelet decomposition. A variant of the frequency-dependent restriction of the spectral components is proposed, which is determined for each of the subbands. Appropriate values of the compression ratio for the coding method based on the prediction of bit planes for a given set of images are presented.
The high resolution of the latest high-performance mobile display devices has resulted in an increase in the main frame buffer size and related bandwidth, and this is one of the main causes of a reduced battery life. ...
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The high resolution of the latest high-performance mobile display devices has resulted in an increase in the main frame buffer size and related bandwidth, and this is one of the main causes of a reduced battery life. As a means to solve this problem, one-dimensional line-based compression methods have been studies in order to be implemented in the limited chip design environment of the mobile display driver ICs. Conventional lossless compression techniques do not have a high compression ratio enough for complex images to ensure a sufficient power reduction. On the other hand, a wavelet-based 1D SPIHT method has been studied for use as a lossy-compression method with a high compression ratio while keeping the image quality. However, this method requires large hardware resources due to the performance for iterative calculations and sorting process. This paper proposes a novel wavelet-based lossy compression system that can achieve high compression and image quality while maintaining low complexity. The Frequency Adaptive Line Compression composed of 4-level DWT, horizontal predictive coding for the low-frequency regions, frequency selective zero-zone quantization for high-frequency regions, and frequency component entropy coding. Experimental results confirmed that the proposed technique could achieve a higher compression ratio than the one required of conventional lossless compression methods and could also be implemented with a significantly less complexity than the conventional SPIHT method at the same compression ratio.
Cross-layer optimization for efficient multimedia communications is an important emerging issue towards providing better quality-of-service (QoS) over capacity-limited wireless channels. This paper presents a cross-la...
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Cross-layer optimization for efficient multimedia communications is an important emerging issue towards providing better quality-of-service (QoS) over capacity-limited wireless channels. This paper presents a cross-layer optimization approach that operates between the application and physical layers to achieve high fidelity downlink video transmission by optimizing with respect to a quality criterion termed "visual entropy" using Lagrangian relaxation. By utilizing the natural layered structure of wavelet coding, an optimal level of power allocation is determined, which permits the throughput of visual entropy to be maximized over a multi-cell environment. A theoretical approach to optimization using the Shannon capacity and the Karush-Kuhn-Tucker (KKT) conditions is explored when coupling the application with the physical layers. Simulations show that the throughput gain for cross-layer optimization by visual entropy is increased by nearly 80% at the cell boundary as compared with peak signal-to-noise ratio (PSNR).
Modern medical imaging modalities produce increasingly large datasets. This trend can be in contrast with the computation and transmission time requirements coming from critical teleradiology applications. Multidimens...
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ISBN:
(纸本)9781457713033
Modern medical imaging modalities produce increasingly large datasets. This trend can be in contrast with the computation and transmission time requirements coming from critical teleradiology applications. Multidimensional image compression techniques can be considered as enabling solutions on condition that they are able to guarantee a suitable combination of rate- distortion and computational performance which fulfill all the application domain requirements. In this work, we present a parallel version of our 3D Embedded Morphological Dilation coding algorithm that allows a significant reduction of computation costs and the concurrent conservation of coding performance and of other relevant bitstream properties. A comparison with the recently released JPEG2000 part 10 (JP3D) standard put in evidence the value of the proposed solution, especially for teleradiology applications over heterogeneous networks.
Based on analyzing the algorithm of EZW, an improved image coding algorithm is presented. The wavelet coefficients are decomposed into two groups and coded separately. Meanwhile, the subordinate pass is removed and th...
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ISBN:
(纸本)9781424441303
Based on analyzing the algorithm of EZW, an improved image coding algorithm is presented. The wavelet coefficients are decomposed into two groups and coded separately. Meanwhile, the subordinate pass is removed and the location information of significant coefficients does not need to be kept in memory, So that the times of scan in the algorithm of the EZW are reduced. Thereby, the coding speed is much improved and the number of coding symbols is reduced. Simulation result shows that the coding\decoding time is much reduced and the volume of coded stream is much smaller compared with the reference algorithm.
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