共查询到20条相似文献，搜索用时 62 毫秒
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研究了彩色图像水印算法,重点研究了彩色图像空间表示和转换关系、余弦变换、基于奇异值分解算法等。提出了一种彩色水印算法,该算法将彩色图像从RGB空间转换到HSV空间,并提取饱和度S分量,对S分量进行了DCT变换,从而获取低频信息,作为水印嵌入位置;在水印嵌入过程时,采用了基于奇异值分解的算法进行嵌入水印。为了检测该算法的鲁棒性,对该算法进行了加入高斯噪声、椒盐噪声、JEPG压缩、几何等方式攻击。结果表明,该算法能有效地抵抗JPEG压缩攻击,对加入噪声攻击也表现了较好的鲁棒性。 相似文献
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《东南大学学报》2015,(3)
为了能够更加有效地恢复受混合高斯和脉冲噪声污染的彩色图像,采用基于四元数的彩色图像整体处理方案,提出了一种彩色图像混合噪声去噪算法.首先,通过一个纯四元数矩阵表征一幅彩色图像;然后,根据高斯噪声和脉冲噪声的不同特性,采用基于四元数方向矢量排序统计的算法检测脉冲噪声位置;最后,将针对高斯噪声的基于四元数最优权值的非局部均值滤波器进行改进以应用于混合噪声图像去噪,在权值计算时不考虑已被检测出的脉冲噪声点.对5幅标准图像的实验结果表明,所提算法的去噪效果优于目前常用的ROR-NLM(robust outlyingness ratio-nonlocal means)算法和最优权值混合滤波器. 相似文献
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提出了一种通过求解L1范数最小化问题来重建四元数信号的算法,并且同时考虑了有噪声和没有噪声2种应用场景.该算法首先将四元数域的L1范数最小化问题转化为实数域的二次锥规划问题,然后通过工具包如SeDuMi来解决这个二次锥规划问题.为了验证所提出算法的正确性和有效性,进行了相关的数值试验.试验结果表明:在没有噪声的情况下,在某些实际可接受的条件下原始信号的精确重建是可以实现的;在有噪声的情况下,所提出的算法对于测量中的加性噪声具有鲁棒性.该算法可以被应用于四元数域基于压缩感知理论的信号重建中. 相似文献
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《实验室研究与探索》2016,(5)
针对藏族壁画特点在采集图像时采用一种基于小波压缩的感知算法,利用改进的小波变换,分解图像高频分量和低频分量,并进行稀疏变换,达到采样压缩。图像重构利用压缩感知OMP算法重构图像,实验表明,原始图像分块数和随机矩阵不变时,采样率越大,PSNR越小,重构的图像也越清晰,针对藏族壁画算法有效。 相似文献
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基于四元数矩阵彩色图像奇异值分解,得到表征彩色图像的不同分量的奇异值,运用分形快速确定图像的拐点。该方法具有快速和简单可行的优点。以受噪声污染图像为例,该方法针对彩色图像去噪具有较好的效果。 相似文献
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压缩感知是信号处理领域的新理论,用于目标跟踪算法时可在大量底层特征中提取出少量重要信息,减少计算量,提高算法速度。传统的基于压缩感知的跟踪算法,为了保证算法速度,对压缩后的特征简单建模,准确性还有待提高。提出一种基于协方差矩阵的压缩感知跟踪算法,先利用压缩感知原理获取压缩后的Haar特征,再利用协方差矩阵融合Haar特征区域内的底层多维特征,以此构建目标模型,并通过搜索当前目标区域的邻域,利用流形空间上的距离度量算法匹配最佳目标,从而提高算法准确性。 相似文献
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提出了一种彩色图像半脆弱水印认证方案,该方案彩色图像转换成灰度图像,并进行了小波压缩后,获得水印图像;在水印嵌入时,首先将彩色图像从RGB空间转换到HSV空间中,对饱和度S分量进行了DCT变换后,获取低频分量,作为水印嵌入的位置,然后将水印图像进行基于奇异值分解算法,从而嵌入水印;在生成认证码阶段,首先对嵌入水印后的图像矩阵中的元素的低位置零,将嵌入水印后的图像进行了HASH运算,生成认证码,并进行了基于LSB运算实现认证码隐藏;为检测该方案的鲁棒性和脆弱性,进行了实验。结果表明,该方案对JPEG、叠加噪声攻击能体现出较好的鲁棒性,对篡改攻击能准确检测和确定篡改的位置,符合半脆弱水印认证的要求。 相似文献
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目前大多数压缩域数字视频水印算法都在视频信息的I帧嵌入信息,没有充分挖掘P、B帧的容量.本文通过分析运动矢量的数据统计特性,提出一种基于运动矢量相位统计特性来隐藏水印信息的视频水印算法.该算法最大特点是利用运动矢量相角角度抖动的基本思想将水印信息嵌入到运动矢量中.算法简单、实用.同时利用矩阵编码来解决运动矢量修改率有可能过高问题.实验表明通过该算法具有很好的鲁棒性和不可感知性,能够抵抗帧删除等同步攻击以及基于视频内容的攻击. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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唐芳 《读与写:教育教学刊》2008,5(6)
During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context. 相似文献