共查询到18条相似文献,搜索用时 109 毫秒
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提出了一种小波域自适应盲水印算法,采用(7,4)汉明码技术进行纠错编码。基于整数小波变换,在中高频区采用不重复零树小波编码,自适应的量化小波系数,将水印嵌入到重要系数上。水印提取过程不需要原始图像的参与。实验结果表明,算法自适应性强,实现速度快,具有较好的不可见性,对常见的JPEG压缩、滤波、加噪、剪切等攻击具有较强的鲁棒性。 相似文献
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针对可视电话、视频电视会议等领域经常出现的视频头肩序列图像,提出了一种面向人脸检屿跟踪的视频分级小波编码方法,在极低比特率下,解码端仍能获得视觉质量较好的恢复序列图像。 相似文献
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提出一维小波与三维DCT(离散余弦变换)相结合的视频图像压缩算法,可有效地改善XYZ压缩方法在高压缩比时的性能。该方法不涉及运动估计和运动补偿,复杂度低。实验结果表明,这种算法能快速、高质量地压缩视频图像。 相似文献
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码率控制技术用来调整并控制视频编码器的输出比特率,以满足带宽要求和保持平稳的输出码流,并获取在质量和带宽利用上的最佳均衡。根据编码视频帧的复杂性及其编码比特来调解量化步长,达到降低最大码率的目的。结果表明,采用的该算法在不影响PSNR的情况下,码率极值得到一定程度的控制。 相似文献
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真正三维小波变换技术及在视频图像编码中的应用 总被引:3,自引:0,他引:3
把图像信号当作真正三维信号处理,导出三维空间正交小波基形式。用三维S.Mallat算法来实现三维信号的小波变换,并将其应用在视频图像的编码中。结果表明,低频3-D子带包含有大部分信息,代表图像序列的上下文信息;量化矩阵取值可以调整变化,压缩比最大可达160。因此这种编码方法的性能是十分优越的。 相似文献
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通过构造特别的映射、整函数和BP神经网络,获得一套基于神经网络的无损数据压缩方案。由于该方案能压缩已被小波编码压缩过的数据,因此将其嵌套入一好的小波编码系统就可以获得一种基于小波与神经网络的高效图像数据压缩方案。实验证明,该高效方案对于Lenna图像的压缩比为43∶1, 并且恢复的图像有较好的视觉效果。 相似文献
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叙述了视频信号处理中的小波变换的应用,在介绍了视频采集系统基本结构和功能的基础上,首先叙述了用小波变换检测视频信号的各参数的方法,然后讨论了如何在具体设备当中实时实现小波变换,提出了用“双存储器”实现的方法。 相似文献
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Mohammed A. Al-Mohimeed C. C. Li 《International journal of imaging systems and technology》1998,9(4):214-229
There has been rapid progress in the application of wavelet transforms to image and image sequence compression. The standard discrete wavelet transform lacks transition invariance in image decomposition which will affect the accuracy of motion estimation from the decomposed subimages in video coding. In this article, we present a study of applying an almost shift-invariant wavelet transform with “oversampled frames” to image sequence compression. With minimal oversampling and biorthogonal spline wavelets in the almost shift-invariant wavelet transform, motion vectors can be more accurately estimated, contributing toward fewer prediction errors in comparison to those obtained with the standard discrete wavelet transform. Thus, an improved compression ratio can be obtained. We present two new algorithms, the full-motion oversampling algorithm (FMOS) and the reduced search multiresolution motion estimation algorithm (MRME), for estimating motion fields at different scales and in different subimages. In the latter, motion vectors at a higher resolution are approximated by the motion vector estimates at a lower resolution through proper scaling. Experiments were performed on three video sequences with a variety of motions including slow, fast, and zooming. Our results have shown that both algorithms, FMOS and MRME, using the almost shift-invariant oversampled frame wavelet transform have reduced prediction errors and enhanced the compression performance in terms of peak-signal-to-noise ratio (PSNR) for the same bit rate when compared to the existing full motion standard algorithm. © 1998 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 9, 214–229, 1998 相似文献
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Shinfeng D. Lin Shih‐Chieh Shie Kuo‐Yuan Lee 《International journal of imaging systems and technology》2005,15(2):123-130
In this article, an efficient image coding scheme that takes advantages of feature vector in wavelet domain is proposed. First, a multi‐stage discrete wavelet transform is applied on the image. Then, the wavelet feature vectors are extracted from the wavelet‐decomposed subimages by collecting the corresponding wavelet coefficients. And finally, the image is coded into bit‐stream by applying vector quantization (VQ) on the extracted wavelet feature vectors. In the encoder, the wavelet feature vectors are encoded with a codebook where the dimension of codeword is less than that of wavelet feature vector. By this way, the coding system can greatly improve its efficiency. However, to fully reconstruct the image, the received indexes in the decoder are decoded with a codebook where the dimension of codeword is the same as that of wavelet feature vector. Therefore, the quality of reconstructed images can be preserved well. The proposed scheme achieves good compression efficiency by the following three methods. (1) Using the correlation among wavelet coefficients. (2) Placing different emphasis on wavelet coefficients at different decomposing levels. (3) Preserving the most important information of the image by coding the lowest‐pass subimage individually. In our experiments, simulation results show that the proposed scheme outperforms the recent VQ‐based image coding schemes and wavelet‐based image coding techniques, respectively. Moreover, the proposed scheme is also suitable for very low bit rate image coding. © 2005 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 15, 123–130, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20045 相似文献
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本文基于小波变换研究了分形图像压缩系统.根据小波系数的能量分布特性,给出了新的小波树定义与分类方法,并在小波域内建立了具有双伸缩因子的压缩映射.在将新的压缩映射应用于图像编码过程时,结合小波嵌入式零树编码思想给出了新的小波分形图像压缩方法.数值实验给出了本文方法与已有方法的比较. 相似文献
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