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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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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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小波变换域双谱分析及其在滚动轴承故障诊断中的应用 总被引:15,自引:3,他引:15
工程信号不仅会受到高斯噪声干扰,而且也会受到非高斯噪声干扰。而传统双谱分析方法从理论上仅能抑制高斯噪声,但对非高斯噪声是无能为力的。针对传统双谱存在的不足,将小波变换和双谱分析结合,提出了一种基于小波变换域非参数化双谱故障诊断方法,并应用到滚动轴承故障诊断中。考虑到滚动轴承信号幅值调制特点,在本方法中,对处理信号采用了希尔伯特变换技术,以进行解调。实验结果表明,小波域双谱优于传统双谱,特别是在非高斯噪声情况下,小波域双谱更有优势;研究为滚动轴承故障诊断提供了一种新的有效方法。 相似文献
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目的 为了提高水印算法的不可见性及抗旋转攻击的能力,提出一种基于BSVD分解和Radon变换的NSCT域鲁棒水印算法。方法 首先对水印图像进行Arnold变换,然后对载体图像进行NSCT变换,接着对低频子带进行不重叠分块,最后对各子块进行BSVD分解,选择合适的缩放因子,将水印嵌入奇异矩阵的最大奇异值中。提取水印时,先用Radon变换对含水印信息的载体图像进行校正,再提取出水印信息。结果 实验显示,文中算法具有很好的不可见性,PSNR值均在60 dB之上,并且能够抵抗常规信号的攻击,NC值均大于0.95。结论 该水印算法具有良好的不可见性和鲁棒性,抵抗旋转攻击的能力较强。 相似文献
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印刷中感光乳剂的调制传递函数(MTF)应用及计算 总被引:1,自引:1,他引:0
介绍了MTF的概念,以及MTF在印刷版材感光乳剂中的应用,并以这个为基础,重点分析了正弦波,线扩散函数的傅立叶转换和相干光处理3种方法,特别讨论图像传递过程中的非线性影响.通过对比,指出了3种方法各自的特点以及测量MTF所需的不同条件.最后总结出了MTF精确度的影响因素,能够在合适的条件下给出一个最有效的印刷版材感光乳剂的调制传递函数, 从而保证印刷图像传递的品质. 相似文献
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Ming‐Sheng Chen Wei Sha Xian‐Liang Wu 《International journal for numerical methods in engineering》2009,80(8):1124-1142
A new wavelet matrix transform (WMT), operated by lifting wavelet‐like transform (LWLT), is applied to the solution of matrix equations in computational electromagnetics. The method can speedup the WMT without allocating auxiliary memory for transform matrices and can be implemented with the absence of the fast Fourier transform. Furthermore, to handle the matrix equation of arbitrarily dimension, a new in‐space preprocessing technique based on LWLT is constructed to eliminate the limitation in matrix dimension. Complexity analysis and numerical simulation show the superiority of the proposed algorithm in saving CPU time. Numerical simulations for scattering analysis of differently shaped objects are considered to validate the effectiveness of the proposed method. In particular, due to its generality, the proposed preprocessing technique can be extended to other engineering areas and therefore can pave a broad way for the application of the WMT. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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克服了传统数字水印方案在嵌入水印时要对原始图像数据进行一定修改从而导致嵌入水印图像质量下降的局限性,提出了一个基于离散小波变换和离散余弦变换组合域内鲁棒的自适应零水印算法.算法首先对原始数字图像进行适当层次的离散小波变换,并对得到的小波逼近子图进行离散余弦变换,然后依据待嵌入二值字符水印的大小和相应的系数差值要求自适应... 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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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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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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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