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ATM网中可变比特率小波视频编码和码率控制 总被引:2,自引:0,他引:2
本文提出了小波视频编码系统及其码率控制的新方法。对原始图像序列进行时间、水平和垂直三维小波分解,并采用改进的等级树集合分区的算法对小波系数进行量化。 相似文献
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建立了用于移动无线互联网接入的视频编码转换模型,提出了自适应运动矢量估值方法.将编码转换码率控制分为图像层控制和宏块层两级,首先在总体上对每帧图像的编码比特数进行预分配,然后采用小波变换系数来表征图像特征,为帧内不同特征的宏块选用不同的量化因子,提出了一种新的码率控制策略.模拟实验表明:该方法在视频图像质量没有明显失真的前提下,提高了视频编码转换速度;编码转换输出码流和编码转换缓冲区占用量较稳定,重建图像的信噪比得到了明显的改善. 相似文献
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根据缓存器的状态和信道速率,为待编码帧在图像层上预分配目的编码比特数,并使用小波变换系数来表征图像特性,继而为帧内每一具体宏块选定量化因子,提出了基于图像特征的码率控制策略。仿真结果表明,该码率控制策略能有效地避免缓存器出现上、下溢的情况,并使输出码率趋于稳定。 相似文献
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提出了一种基于提升格式小波的SPIHT图像压缩算法,该算法采用LS9/7进行小波变换,然后采用SPI-HT算法对变换系数进行编码,可实现任意码率的压缩.该算法具有运算简单,编码速度快等优点.实验结果表明,设计的算法是一种有效的图像压缩算法,能实现图像的快速压缩编码,其图像编解码时间和重构图像质量均优于原算法. 相似文献
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MPGE—2视频编码流的码率变换技术的研究 总被引:1,自引:0,他引:1
比较了分析两种视频编码流的码率变换器结构的性能,提出了一种在图像内按宏块的复杂度分配目标码字,并直接控制交流DCT系统编码比特数的码率控制算法。本文提出的码率控制算法优于TM5的码率控制算法。 相似文献
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图像信号的码率较高,必须经过压缩才能有效传输,多年来,这种压缩就叫信源编码。由于小波变换的压缩码率高,并且克服了正交变换中的方块效应,因此是一种强有力的信源编码的压缩方法之一,本就小波变换的基本原理,特点,进行了概括描述。 相似文献
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Lin Gang Tian Tiehong Liu Zemin 《电子科学学刊(英文版)》2000,17(3):219-224
This paper presents a new video coding system based on wavelet transform and its rate control scheme over ATM networks. First, three dimensional wavelet transform is performed for the original image sequence, and an extension of set partitioning in hierarchical trees algorithm is employed to quantize the wavelet coefficients. Then, the output rate of the coder is controlled at group of frame scale, ensuring that it conforms to the parameters of a leaky bucket controller. Several leaky buckets with different sizes are discussed too. Simulation shows the efficiency of this codec and the effectiveness of the proposed rate control scheme. 相似文献
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该文提出了一种Contourlet变换和小波变换相结合,使用新的空间方向树的类似SPIHT编码算法。该算法先对图像进行Contourlet变换,再对变换后的低频子带进行多级小波变换,然后根据变换后系数的结构特性,借鉴小波SPIHT编码思想,构造了一种新的空间方向树,实现了对变换后系数的类似SPIHT编码。仿真实验结果表明,该算法与小波变换,Contourlet变换和基于小波的Contourlet变换的SPIHT算法相比,重构图像保留了更多的纹理和细节信息,并且在低比特率下具有较高的峰值信噪比。 相似文献
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小波图像的膨胀-游程编码算法 总被引:3,自引:0,他引:3
提出了一种基于形态膨胀运算和游程编码的新型小波编码器膨胀-游程(Dilation-Run)算法。编码器根据图像小波变换后重要系数的带内聚类特性和重要系数分布的带间相似性,利用数学形态学中的膨胀运算搜索并编码各聚类中的重要系数;同时使用一种高效的游程编码技术对各聚类的种子系数,即膨胀运算起始点的位置进行编码,从而避免了小波图像中非重要系数的逐个编码。编码器算法简单,并且基于位平面实现,因此输出码流具有渐进性。实验结果表明,膨胀-游程算法的性能优于零树小波编码器SPIHT,并能与两种形态学小波编码器MRWD 和SLCCA的性能媲美。对于聚类特性显著的图像,算法的性能则优于上述形态学小波编码器。 相似文献
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A fast and low memory image coding algorithm based on lifting wavelet transform and modified SPIHT 总被引:1,自引:0,他引:1
Due to its excellent rate–distortion performance, set partitioning in hierarchical trees (SPIHT) has become the state-of-the-art algorithm for image compression. However, the algorithm does not fully provide the desired features of progressive transmission, spatial scalability and optimal visual quality, at very low bit rate coding. Furthermore, the use of three linked lists for recording the coordinates of wavelet coefficients and tree sets during the coding process becomes the bottleneck of a fast implementation of the SPIHT. In this paper, we propose a listless modified SPIHT (LMSPIHT) approach, which is a fast and low memory image coding algorithm based on the lifting wavelet transform. The LMSPIHT jointly considers the advantages of progressive transmission, spatial scalability, and incorporates human visual system (HVS) characteristics in the coding scheme; thus it outperforms the traditional SPIHT algorithm at low bit rate coding. Compared with the SPIHT algorithm, LMSPIHT provides a better compression performance and a superior perceptual performance with low coding complexity. The compression efficiency of LMSPIHT comes from three aspects. The lifting scheme lowers the number of arithmetic operations of the wavelet transform. Moreover, a significance reordering of the modified SPIHT ensures that it codes more significant information belonging to the lower frequency bands earlier in the bit stream than that of the SPIHT to better exploit the energy compaction of the wavelet coefficients. HVS characteristics are employed to improve the perceptual quality of the compressed image by placing more coding artifacts in the less visually significant regions of the image. Finally, a listless implementation structure further reduces the amount of memory and improves the speed of compression by more than 51% for a 512×512 image, as compared with that of the SPIHT algorithm. 相似文献
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This paper presents new wideband speech coding and integrated speech coding-enhancement systems based on frame-synchronized fast wavelet packet transform algorithms. It also formulates temporal and spectral psychoacoustic models of masking adapted to wavelet packet analysis. The algorithm of the proposed FFT-like overlapped block orthogonal wavelet packet transform permits us to efficiently approximate the auditory critical band decomposition in the time and frequency domains. This allows us to make use of the temporal and spectral masking properties of the human auditory system to decrease the average bit rate of the encoder while perceptually hiding the quantization error. The same wavelet packet representation is used to merge speech enhancement and coding in the context of auditory modeling. The advantage of the method presented in this paper over previous approaches is that perceptual enhancement and coding, which is usually implemented as a cascade of two separate systems, are combined. This leads to a decreased computational load. Experiments show that the proposed wideband coding procedure by itself can achieve transparent coding of speech signals sampled at 16 kHz at an average bit rate of 39.4 kbit/s. The combined speech coding-enhancement procedure achieves higher bit rate values that depend on the residual noise characteristics at the output of the enhancement process 相似文献
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基于小波图像编码的远程监控系统的设计与实现 总被引:1,自引:0,他引:1
小波变换由于其多分辨率特性而特别适合图像编码。该文设计了一种基于小波图像编码的远程监控系统。整个系统由本地监控端和远程主控端组成。本地监控端包括图像采集、小波变换图像编码和发送3个模块。小波变换图像编码由二维小波变换和零树编码组成。设计了监控端各个模块的硬件结构,编写了其硬件结构的Verilog HDL模型,进行了仿真和逻辑综合,并用FPGA进行了验证。编写了主控端的远程接收、控制软件,成功实现了基于小波图像编码的远程监控系统。 相似文献
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