共查询到20条相似文献,搜索用时 62 毫秒
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基于脊波变换的扩频水印算法 总被引:1,自引:1,他引:0
针对脊波变换域比小波变换域更适合表示图像线状边缘的奇异性的特征,本文设计出一种新的图像水印算法,即将图像分块脊波变换,在脊波变化域上的高频系数中加性地嵌入经零均值互不相关伪随机序列扩频调制后的水印。实验结果表明,本文算法不仅可以抵抗如压缩、加噪、滤波和剪切等各种常见攻击,还能抵抗图像灰度增强和减弱攻击,与小波域水印算法的比较也说明了本文算法的优势。 相似文献
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架构于双树轮廓波及GGD模型的纹理图像检索 总被引:1,自引:0,他引:1
提出一种基于双树轮廓波变换的纹理图像检索方法.双树轮廓波由塔型双树方向滤波器组构建,它保持了轮廓波灵活的方向选择性,同时克服了传统轮廓波不具有移不变性的缺点.根据双树轮廓波系数的统计特性,本文利用广义高斯分布对各子带进行建模,采用矩估计法提取模型参数,并用KL距离度量图像之间的相似度,实现纹理图像检索.为评价检索性能,从Brodatz图库创建了包含800幅纹理图像的数据库.实验结果表明,本文算法的平均检索率比基于小波和轮廓波的方法分别提高了10.46%和6.94%,而且保持了较高的计算效率. 相似文献
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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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基于DT-CWT和SVM的纹理分类算法 总被引:4,自引:2,他引:2
提出了一种基于双树复数小波变换(DT-CWT)和支持向量机(SVM)的纹理分类算法.双树复数小波变换不仅具有实数小波的诸多优点,而且还具有近似平移不变性、良好的方向选择性和低冗余度,并且能对图像进行完全重构,能够更好地刻画纹理的特性;支持向量机算法是近年发展起来的性能优越的分类算法,比传统分类器有很大的优越性:避免了局部最优解和"维数灾"问题,其最优分类超平面的思想能够提高分类准确度.该方法用双树复数小波对纹理图像进行滤波并在各方向子带上进行重构,再计算其局部能量函数得到每个像素的特征向量,最后利用支持向量机算法实现对纹理图像像素的分类.将本方法与其它的分类算法进行比较,实验结果表明,提出的算法能有效地提高正确分类率. 相似文献
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针对遥感图像纹理丰富、空间相关性弱,普通压缩算法容易造成高频信息丢失的特点,本文利用小波包优良的高频分析能力,提出一种结合SPIHT的小波包编码算法.该算法采用类似SPIHT算法的零树结构,通过重新定义方向树,即扩展方向树,改变小波包各节点之间的对应关系,解决小波包分解时产生的"父冲突"问题.同时,对扩展方向树的合理性进行了实验验证,并结合SPIHT算法实现了整个编解码.实验结果表明,对于富含纹理的遥感图像,在1bpp的压缩率下,该算法峰值信噪比(PSNR)超出SPIHT算法0.5-1dB,且视觉效果更好. 相似文献
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基于多分辨率分析的数字图像自动聚焦算法研究 总被引:1,自引:1,他引:1
本文提出一种基于小波变换的多分辨率分析方法来实现数字图像自动聚焦的新算法。本算法通过对小波变换后清晰图像和模糊图像的高频系数的能量值进行计算比较,从而可以判断图像是否聚焦。计算机仿真也证实了该算法的正确性和有效性。 相似文献
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利用小波变换的多尺度对图像纹理特征良好表达的特点,用小波变换提升算法图像纹理特征进行提取,从而达到较好的分割效果。 相似文献
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Jos J. Amador 《International journal of imaging systems and technology》2003,13(4):201-207
This article presents a tractable and empirically accurate algorithm realizing a midlevel visual process for pattern recognition. The algorithm takes advantage of hypotheses provided by a high‐level visual process, thereby, attempting to extract a region in an image based on these hypotheses. The main focus is to recognize quadrilateral as well as arbitrarily shaped objects from synthetic and real‐world images. The novel approach is based on a study of the Hough Transform and its generalized version. To show overall usefulness of the algorithm, an extensive series of experiments was performed. In particular, occlusion and multiple object‐instances were tested, indicating the effectiveness of this work's approach.© 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 13, 201–207;2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10056 相似文献
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Gengsheng L. Zeng Jiangsjemg You Qiu Huang Grant T. Gullberg 《International journal of imaging systems and technology》2007,17(4):219-223
Recently we published two explicit formulae for finite inverse Hilbert transforms (You and Zeng, Inv Probl 22 (2006), L7‐L101). This paper presents a straightforward proof of the formulae, the data requirements, and some computer simulations to verify the formulae. Examples of region‐of‐interest tomography using truncated projections and the first formula of the finite inverse Hilbert transform are shown. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 219–223, 2007 相似文献
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The purpose of this paper is to carry out the assessment of effect of cycle spinning on wavelet- and curvelet-based noise reduction methods on brain CT images. In particular, multiscale curvelet- and wavelet-based denoising methods are evaluated with and without cycle spinning. This assessment is focused not only on the noise suppression but also on fine details preservation. The experimental results show that the cycle spinning-based curvelet method outperforms not only other curvelet-based methods but also the wavelet-based methods. The quality assessment parameters taken in this paper are signal-to-noise ratio (SNR), peak-signal-to-noise ratio (PSNR), universal quality index (UQI), structural similarity index metrics (SSIM), and edge keeping index (EKI). 相似文献
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3种频域数字水印算法的分析和比较 总被引:5,自引:5,他引:0
阐述了离散傅里叶算法(DFT)、离散余弦算法(DCT)、离散小波变换算法(DWT)这3种常用的频域数字水印算法的原理,并分别采用不同算法对数字图像进行了水印嵌入,检测其峰值信噪比(PSNR)和相关系数(NC)的值,分析并比较了这3种算法的优缺点,证明了离散小波变换在频域算法中能够得到最好的效果。 相似文献
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In this paper, we propose a new quick response (QR) code-based non-linear technique for image encryption using Shearlet transform (ST) and spiral phase transform. The input image is first converted into a QR code and then scrambled using the Arnold transform. The scrambled image is then decomposed into five coefficients using the ST and the first Shearlet coefficient, C1 is interchanged with a security key before performing the inverse ST. The output after inverse ST is then modulated with a random phase mask and further spiral phase transformed to get the final encrypted image. The first coefficient, C1 is used as a private key for decryption. The sensitivity of the security keys is analysed in terms of correlation coefficient and peak signal-to noise ratio. The robustness of the scheme is also checked against various attacks such as noise, occlusion and special attacks. Numerical simulation results are shown in support of the proposed technique and an optoelectronic set-up for encryption is also proposed. 相似文献
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某些微分方程和相应的积分方程之间的关系被讨论;这些微分方程通过边境小波变换可被转换成相应的积分方程,它们不仅在弱收敛意义下而且在范围数收敛意义下是等价的;关于这些微分方程的讨论就与相应的积分方程的讨论联系起来。 相似文献
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We present a novel multiple-image encryption algorithm by combining log-polar transform with double random phase encoding in the fractional Fourier domain. In this algorithm, the original images are transformed to annular domains by inverse log-polar transform and then the annular domains are merged into one image. The composite image is encrypted by the classical double random phase encoding method. The proposed multiple-image encryption algorithm takes advantage of the data compression characteristic of log-polar transform to obtain high encryption efficiency and avoids cross-talk in the meantime. Optical implementation of the proposed algorithm is demonstrated and numerical simulation results verify the feasibility and the validity of the proposed algorithm. 相似文献
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It is shown that wavelet analysis can be used to process medical data (in particular ECGs) as being more promising than other methods, since it allows one to observe key diagnostic features and obtain a time-frequency characterization. 相似文献