CASIA OpenIR  > 毕业生  > 博士学位论文
自适应图像压缩编码和图像水印技术的研究
黄继武
Subtype工学博士
Thesis Advisor戴汝为
1998-11-01
Degree Grantor中国科学院自动化研究所
Place of Conferral中国科学院自动化研究所
Degree Discipline模式识别与智能系统
Keyword图象压缩 自适应编码 分类编码 分类器 分割编码 Dct 图象水印 嵌入对策 自适应水印 有意义水印 Image Compression Adaptive Coding Classified Coding Classifier Segmentation-based Coding Dct Image Watermarking Embedding Strate
Abstract图象数据压缩和数字图象水印技术是多媒体信号处理领域中二个十分重要 的研究方向。本论文主要研究自适应图象压缩编码算法和自适应图象隐形水印算 法。主要贡献有: 1.提出了二种自适应BTC算法。通过采用基于边缘的分割和视觉系统对比 度特性,实现了自适应BTC编码。所提出的算法在保持BTC优点的同 时,压缩比与经典BTC相比有明显的改善。 2.提出了一个用于分类自适应块编码的JND分类器,其性能与最常用的局 部方差分类器相似,但计算量明显下降。 3.在对各种块分类器进行分析的基础上,我们提出了一个综合了JND、多 项式近似误差和空间频率谱多种分类参数的集成分类器,使分类性能有 较大程度的提高。利用该集成分类器设计的分类自适应块编码算法达到 了较高的压缩比。 4.在分析视觉系统对比度特性的基础上,提出了一个用于图象压缩的图象 四叉树分割标准。该标准考虑了视觉系统的对比度掩蔽特性,利用视觉 敏感度来测量一个区域的均匀度,提高了分割过程与视觉系统的匹配程 度。应用这一标准,我们提出了一个基于四叉树的分割/分类混合编码 算法,算法性能大大优于JPEG国际标准。 5.从信号处理的角度,分析了块效应的空域特征,提出了一种基于广义中 值滤波的空间移变自适应后处理算法,有效地改善了重建图象的主、客 观质量。 6.分析了块效应在频域中的特征,提出了频域的块效应模型。应用该模型, 有效地消除了边缘图象中的块效应。在此基础上,利用滤波后的边缘做 辅助分析,提出了一个对译码图象进行后处理的自适应滤波算法。 7.提出了一种基于块分类的DCT域自适应水印算法。利用视觉系统的照度 掩蔽性和纹理掩蔽性实现水印分量的自适应嵌入,所实现的隐形水印对 常见图象处理和噪声干扰具有很好的稳健性。 8.根据对DCT域DC和AC分量的定性/定量分析,提出了一个新的水 印嵌入对策。与通常的嵌入对策不同,所提出的对策指出了DC分量作 为水印载体的重要价值。 9.应用上述嵌入对策,结合空域的块分类,我们提出了一个利用DC分量 的自适应水印算法,所实现水印的稳健性有了很大的提高。 10.探讨了有意义水印的理论,基于Gaussian噪声模型,理论上分析了图象 可允许嵌入信息的容量。 11.利用扩频通信的原理,提出一个有意义水印的编码和检测方法。对于 Gaussian噪声,在26dB的信噪比
Other AbstractImage data compression and image watermarking are two important subareas in multimedia signal processing. This thesis is about on adaptive image compression and adaptive image watermarking algorithms. The main contributions in this thesis are as follows: 1. Two adaptive BTC algorithms are presented. By using edge-based segmentation and contrast features of human vision system (HVS), we improve the compression performance efficiently while remaining the main merits of conventional BTC. 2. We propose a JND-based classifier used in classified block coding that utilizes the visual features of HVS. The classifier is almost as efficient as the most commonly utilized classifier based on the local variance, but has lower computational complexity. 3. Motivated by the analysis on some classifier commonly used, we propose an integrated classifier that is composed of JND-based classifier, the polynomial approximation error based classifier, and the spatial-frequency spectrum based classifier. The integrated classifier performs much better than those single parameter classifiers. The algorithm applying the classifier achieves high compression ratio. 4. By analyzing visual models, we derive a novel quadtree-based segmentation criterion based on luminance masking. The criterion measures the uniformity of a block by using visual sensitivity and so matches the visual features of HVS well. A hybrid coding algorithm applying above criterion is then presented. The algorithm exhibits much better performance than JPEG. 5. We analyze the blocking effects in spatial domain and then propose an adaptive space-variant postfiltering algorithm. The algorithm improves both the subjective and objective quality of reconstructed images efficiently. 6. We find a feature pattern of artifacts in frequency domain and the notch filtering of the edge image extracted from a decoded image. An adaptive postprocessing algorithm based on a neighborhood analysis on the notch- filtered edges is proposed. 7. A classification-based image watermarking scheme in DCT domain is proposed. It is adaptive in that different strength of watermark is applied to different blocks according to block classification. In the classification, luminance and texture masking are taken into account. The invisible watermarks thus generated are robust against common signal processing and noise. 8. Based on a quantitative analysis on magnitude of DCT components, a new embedding strategy for image watermarking is proposed. Different from the popular strategies, we argue that more robustness can be achieved if watermarks are embedded in DC components since DC components have much larger perceptual capacity than any AC components. 9
shelfnumXWLW489
Other Identifier489
Language中文
Document Type学位论文
Identifierhttp://ir.ia.ac.cn/handle/173211/5692
Collection毕业生_博士学位论文
Recommended Citation
GB/T 7714
黄继武. 自适应图像压缩编码和图像水印技术的研究[D]. 中国科学院自动化研究所. 中国科学院自动化研究所,1998.
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