共查询到20条相似文献,搜索用时 15 毫秒
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研究了如何通过解码端含有边信息时获得未知信源的数据,即加噪信源的量化、编码及函数重建.将WZ高速量化及变换编码理论扩展到编码端对噪声进行观测的情况,并通过实验说明不同约束条件下的性能特点.验证了在构建最佳量化器的过程中能保持近似相同的率失真性能. 相似文献
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Yig-Shyang Lin Tsann-Shyong Liu Long-Wen Chang 《Multidimensional Systems and Signal Processing》1997,8(3):295-313
Bit rate control has been proved to be an important technique used to transmit the variable rate bit stream over a fixed rate channel in MPEG coding. In this paper, a hybrid algorithm is proposed to achieve the rate control and obtain a good picture quality. In the picture layer, the algorithm estimates numbers of bits required for different type of frames. In the macroblock layer, it utilizes the predictive and adaptive perceptual techniques in the regulation of the quantization scale to allocate the target bits. In the upper and left boundary of the picture, the macroblocks are quantized with the perceptual basis to adjust the quantization scale and in the other part of the picture a predictive method is used to update the quantization scale. By using the proposed scheme, the distortion of coding is uniformly distributed in the picture layer as well as in the macroblock layer and better bit rate control is achieved. 相似文献
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In this paper, block constrained trellis coded vector quantization (BC‐TCVQ) is presented for quantizing the line spectrum frequency parameters of the wideband speech codec. Both a predictive structure and a safety‐net concept are combined into BC‐TCVQ to develop the predictive BC‐TCVQ. The performance of this quantization is compared with that of the linear predictive coding vector quantizer used in the AMR‐WB codec, demonstrating reductions in spectral distortion. 相似文献
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本文在讨论JPEG标准压缩过程的基础上,提出了自适应优化匹配量化表的JPEG图像压缩方法。该方法根据每个图像子块不同的频率特性确定不同的量化表。本文通过一系列的图像实际压缩实验,证明了该方法的有效性和可行性。 相似文献
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Jeremy Lubkin Gert Cauwenberghs 《Analog Integrated Circuits and Signal Processing》2002,30(2):149-157
We present a mixed-mode VLSI chip performing unsupervised clustering and classification, implementing models of Fuzzy Adaptive Resonance Theory (ART) and Learning Vector Quantization (LVQ), and extending to variants such as Kohonen Self-Organizing Maps (SOM). The parallel processor classifies analog vectorial data into a digital code in a single clock, and implements on-line learning of the analog templates, stored locally and dynamically using the same adaptive circuits for on-chip quantization and refresh. The unit cell performing fuzzy choice and vigilance functions, adaptive resonance learning and long-term analog storage, measures 43 m×43 m in 1.2 m CMOS technology. Experimental learning results from a fabricated 8-input, 16-category prototype are included. 相似文献
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为实现高质量的极低速语音编码,提出一种基于压缩感知理论的线谱对(LSP)参数降维量化算法。编码端利用压缩感知理论对超帧LSP高维矢量进行降维处理,将原始LSP参数投影到低维空间,得到低维测量值,然后采用分裂矢量量化算法对测量值进行量化;解码端以量化后的测量值为已知条件,利用正交匹配追踪算法重构出原始LSP高维矢量。实验结果表明,本算法相对低速语音编码中的矩阵量化方案,平均谱失真降低了0.23dB,相对基于DCT变换的降维量化方案,平均谱失真降低了0.13dB。这种先降维再量化的思想可以大幅减少编码所需的比特数及码本存储复杂度,有效降低语音编码速率,并且合成语音可懂度、自然度较高,音质虽有所失真,但基本上感觉不到明显的听觉质量下降。 相似文献
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Tsung-Yuan Chang Steven B. Bibyk 《Analog Integrated Circuits and Signal Processing》2001,26(3):205-220
The exact analysis of second order bandpassDelta-Sigma modulator with sinusoidal inputs isperformed. The results indicate that quantization erroris neither uniformly distributed nor white. Thequantization error spectrum is purely discrete andsymmetric with one forth of sampling frequency, and thelocations of these discrete frequency components arestrongly dependent on input amplitudes. Similar resultsare also observed for passband communication signals,such as quadrature amplitude modulation. From theanalysis, crosscorrelation between quantization error andsinusoidal input was shown to exist but can be cancelledout by proper design of the noise shaping function. Crosscorrelation can degrade the performance of thedelta-sigma system. Hence, the exact analysis is anothermethod to enable design for high performance. 相似文献
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用于图像编码的相关矢量量化研究 总被引:8,自引:2,他引:8
当相邻的图像块用矢量量化(VQ)编码时可能出现编码地址相同的情况,尤其是在图像的平滑区。为了减少相邻块间编码地址的相关性,本文提出了一种相关矢量量化方案,采用相关码书与改进的自组织特征映射(ISOFM)码书同时编码一个窗口内的四个邻域块,与无记忆类VQ相比,对一幅典型的“Lenna”图象,编码过程中所需计算量减少一半,比特率减少40%,由于在Kohonen自组织神经网络的训练过程中,对边缘类矢量采 相似文献
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针对复杂背景下红外弱小目标图像的背景抑制难题,从图像采集环节考虑,根据自适应差分量化理论,提出了一种基于自适应背景抑制的红外弱小目标图像采集方法.其基本思想是:根据红外弱小目标图像背景杂波的相关性,利用自适应预测器,由已采集的像素信息实时估计出下一时刻背景杂波的最佳估计,并将其反馈至原始图像信号输出端,与实际采集图像信号相比较.通过量化残差图像信号来获得预测增益,从而提高采集图像的信噪比.理论分析与仿真实验表明,与传统的直接图像采集方法相比,此方法不仅等效地提高模数转化器的性能,而且能够很大程度地提高采集图像的信噪比(SNR),SNR可由1.43提高到4.57. 相似文献
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稀疏分解能有效分离信号和噪声,因此适用于信号去噪.文中构造了雷达回波稀疏表示的冗余字典,字典原子与目标回波波形匹配,基于该字典的雷达回波信号稀疏度就是目标数.针对稀疏度自适应匹配追踪算法进行低信噪比信号稀疏分解时的不足,提出了一种迭代自适应匹配追踪算法,采用规范化的残差之差作为迭代终止条件,使得稀疏分解过程能依据噪声水平自适应终止,以逐次逼近方式估计信号稀疏度,改善了稀疏分解的精度.仿真实验结果表明,该算法在低信噪比以及稀疏度未知的条件下,实现了雷达回波信号的准确稀疏分解,极大地提高了信噪比. 相似文献
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Bao Changchun 《中国邮电高校学报(英文版)》1996,(1)
One-StepinterpolationPredictiveVectorQuantizationofLSPParameters¥BaoChangchun(DepartmentofTelecommunicationEngineering,Changc... 相似文献
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LD-CELP语音编码算法中矢量量化过程的改进 总被引:1,自引:0,他引:1
本文介绍了LD-CELP算法的基本原理,在分析其编码的矢量量化过程的基础上提出了一种旨在提高编码速度的改进方案.模拟实验表明,改进算法的编码速度平均提高了一倍.虽然信噪比有所下降,但下降幅度仅为1.2dB,依然能够保证编码质量. 相似文献