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通过时Mallat算法和提升小波变换的比较,并分析图像经过小波变换后系数的分布特点,提出了一种新的将提升小波变换和BP神经网络相结合的图像压缩方法.根据小波变换后图像的绝大部分能量都集中在小波变换的低频部分这一特性,利用BP神经网络,对不同的频带子图进行不同压缩比的压缩,从而得到高质量的重构图像.结果表明,该算法不仅有较高的压缩比,而且获得了质量较高的重构图像,对背景简单的图像压缩效果尤为明显. 相似文献
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针对小波变换图像压缩编码方法在高压缩比下得到的重构图像质量往往较差的问题,提出了一种基于谱图小波变换的编码方法.该方法首先将图像转化成图,利用谱图小波变换分解图得到谱图小波系数,这些系数的能量随着尺度的增加而衰减,然后根据谱图小波系数的特性对SPECK算法进行改进,最后对谱图小波系数进行量化,利用改进的SPECK算法对量化后的系数进行压缩编码,并在图像数据量压缩的同时从稀疏系数中恢复原始图像.实验结果表明,该编码方法对自然图像的压缩具有高效性,相比小波变换的压缩方法,重建图像的PSNR有所提高且变化平稳,与此同时还得到更大的压缩比. 相似文献
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提出了一种先去噪再利用小波变换的图像压缩方法,用Matlab软件编程实现算法。实验仿真结果显示,图像在具有高压缩比的同时,重构图像的质量也较优;使用不同的小波基函数,效果不同。 相似文献
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结合小波变换,提出了图像有损压缩预处理的各向异性扩散方案。各向异性扩散在图像平滑中,其不但能够较好地抑制噪声,而且能够很好地保留图像原有的边缘和纹理特征,而小波变换又具有人类的视觉特性。该方案先对图像作小波变换,再根据各子图像的特点,用不同的各向异性扩散方法处理子图,最后压缩重构图像。实验表明,对有损压缩来讲,与已有的方法比较,该方案具有更好的解码质量和更高的压缩比。 相似文献
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小波包是近年来的一个研究热点,在图像处理方面有着很广泛的应用。文中提出了基于小波包的图像压缩及Madab实现方法,加快了图像压缩的进程,取得了很好的实验效果。将图像在小波包最优基下展开,利用小波包最优基极好的空间、尺度定位性,使得图像的小波包变换系数在小波变换域极可能的集中从而使在不降低压缩信号的视频质量情况下,提高了图像的压缩比。 相似文献
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目的针对自组织特征映射(SOFM)算法会出现严重的分块现象和快速小波变换在高压缩比的情况下图像恢复质量差的问题,提出引入神经网络中间神经元(relay neurons)的RSOFM-C矢量量化算法。方法引入了中间神经元的概念,使用中间神经元有效解决了码字利用不均匀的问题,并在神经网络中间层给出了欧氏距离不等式判据,排除不满足失真测度的神经元,减少重复计算,加快学习速度。根据差分脉冲编码调制(DPCM)中的差值信号编码原理将RSOFM-C算法与快速小波变换结合,使用RSOFM-C算法对由快速小波变换得到的图像低频信号进一步压缩。结果在仿真实验中,将本文算法与同类压缩方法进行对比,当压缩比为52%时,本文算法的峰值信噪比(PSNR)达到了39.28 d B,远远高于其他方法。结果表明,本文的压缩算法消除了分块现象,并且在保证高压缩比的同时获得高质量的重构图像。结论实验结果表明,本文提出的引入了中间神经元的快速小波压缩方法,具有高压缩比、高保真、速度快等优点,可以高效地压缩图像。 相似文献
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基于整数小波变换的机载多光谱图像无损压缩 总被引:4,自引:0,他引:4
首先探讨了基于提升方案的整数小波变换,结合线性预测技术,提出了一种机载多光谱遥感图像的无损压缩方法。该方法通过整数小波变换减少图像的空间冗余,然后根据多光谱图像谱间的相关性对整数小波变换后的结果进行预测,并且加进了相关性判断这一环节保证了预测的有效性。算法适合并行处理和硬件实现。对机载64波段多光谱遥感图像的试验结果表明,该方法与改进的预测树方法相比其无损压缩比平均提高了16%,压缩时间缩短了三分之二。 相似文献
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Nick D. Panagiotacopulos Ken Friesen Sukit Lertsuntivit 《Journal of Intelligent and Robotic Systems》2000,28(1-2):39-59
In this paper, we report the results of the application of transform coding image data compression techniques using Daubechies and Coifman wavelets. More specifically, D2, D4, D8, D16, and C6, C12 wavelets were used. The results from these wavelets were compared with those of discrete cosine transform. They clearly demonstrated the superiority of the wavelet-based techniques both in compression ratios and image quality, as well as in computational speed. Two quantization methods were used: non-uniform scalar quantization and pseudo-quantization. Both produced satisfactory results (86–88% compression ratio, and acceptable image quality). 相似文献
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Remote sensing images are hard to achieve high compression ratio because of their rich texture. By analyzing the influence of wavelet properties on image compression, this paper proposes wavelet construction rules and builds a new biorthogonal wavelet construction model with parameters. The model parameters are optimized by using genetic algorithm and adopting energy compaction as the optimization object function. In addition, in order to resolve the computation complexity problem of online construction, according to the image classification rule proposed in this paper we construct wavelets for different classes of images and implement the fast adaptive wavelet selection algorithm (FAWS). Experimental results show wavelet bases of FAWS gain better compression performance than Daubechies9/7. 相似文献
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Compressing still and moving images with wavelets 总被引:4,自引:0,他引:4
The wavelet transform has become a cutting-edge technology in image compression research. This article explains what wavelets are and provides a practical, nuts-and-bolts tutorial on wavelet-based compression that will help readers to understand and experiment with this important new technology.The work in this paper was supported by Summus, Ltd. 相似文献
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图象压缩时如何选择小波基是一个难题,这是由于不同的小波数学特性会对图象的压缩编码产生不同的影响.文中对小波基的正交性、光滑性、消失矩、滤波器长度等一些重要的小波特性对图象压缩性能的影响进行了对比研究.通过仿真分析,得出双正交小波比正交小波具有更优异的性能,一般条件下应尽量选择消失矩大、正则性好的双正交小波,而且应尽量优先保证重构小波的正则性效应,这样才可能得到效果较好的重构图像质量.但是在相同或相似的正则性、消失矩、滤波器长度等条件下,双正交小波较正交小波的性能改进则不是很明显. 相似文献
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A. S. Tolba 《Digital Signal Processing》2002,12(4):408
Tolba, A. S., Wavelet Packet Compression of Medical Images, Digital Signal Processing12 (2002) 441–470The increasing need for efficient image storage and transmission in hospitals imposes heavy requirements on the design of picture archiving and communication systems. Thus new methods are needed for efficient image compression. Recent reviews of wavelets in biomedical applications showed that wavelets should be used with caution and that a particular solution should always be motivated by the problem itself. This study discovers the best design parameters for a data compression scheme applied to medical images of different imaging modalities. The proposed technique aims at reducing the transmission cost while preserving the diagnostic integrity. By selecting the wavelet packet's filters, decomposition level and subbands that are better adapted to the frequency characteristics of the image, one may achieve better image representation in the sense of lower entropy or minimum distortion. Experimental results show that the selection of the best parameters has a dramatic effect on the data compression rate of medical images. Statistical significance tests were performed on the experimental measures to conduct the most suitable wavelet shape for each imaging modality. Image quality measures are used to evaluate the performance of different wavelet filters for different imaging modalities. Image resolution is found to have a remarkable effect on the compression rate. 相似文献
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Best parameters selection for wavelet packet-based compression of magnetic resonance images. 总被引:3,自引:0,他引:3
Transmission of compressed medical images is becoming a vital tool in telemedicine. Thus new methods are needed for efficient image compression. This study discovers the best design parameters for a data compression scheme applied to digital magnetic resonance (MR) images. The proposed technique aims at reducing the transmission cost while preserving the diagnostic information. By selecting the wavelet packet's filters, decomposition level, and subbands that are better adapted to the frequency characteristics of the image, one may achieve better image representation in the sense of lower entropy or minimal distortion. Experimental results show that the selection of the best parameters has a dramatic effect on the data compression rate of MR images. In all cases, decomposition at three or four levels with the Coiflet 5 wavelet (Coif 5) results in better compression performance than the other wavelets. Image resolution is found to have a remarkable effect on the compression rate. 相似文献
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基于提升方法的简单9/7小波滤波器 总被引:12,自引:0,他引:12
本文以构造双正交小波的Cohen-Daubechies-Feauveau定理为基础,利用提升方法构造了一组对称双正交9/7小波滤波器,它与JPEG2000中采用的CDF97小波压缩性能几乎相同,并且它们两者在图象压缩中可以互相作正变换与逆变换,新9/7小波的计算只需要两个浮点运算和16个整数运算,而CDF97小波需要14个浮点运算,因而它能极大地简化和 减小图象压缩和视频压缩的运算量。 相似文献