共查询到19条相似文献，搜索用时 139 毫秒
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黄婕 《连云港职业技术学院学报》2007,20(1):16-19
数字水印将感觉不到的信号嵌入到声频、视频和图像中以实现不同的目的.从有关数字水印的基本原理及其主体框架出发.将数字水印按不同角度划分为不同种类,并从空间域算法、变换域算法、压缩域算法、NEC算法及生理模型算法的角度讨论了数字水印技术,指出未来值得关注的研究领域一是数字水印的基本理论和算法的研究;二是数字水印的标准化研究;三是数字水印的网络应用研究;四是与其他领域先进技术的结合研究. 相似文献
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视频关键帧提取是视频信号处理中的一个重要内容。由于一个镜头中视觉内容的变化具有连续性,本文采用了距离累加的算法;同时,为了提高检测相邻帧间的相似度,本文将颜色特征与运动变化信息相结合,提出一种关键帧提取方法。实验证明,与过去的关键帧提取方法相比,本文算法提取的关键帧能较完整地表现序列图像的运动过程,更有利于对视频内容的理解。 相似文献
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数字水印技术广泛应用于数字媒体的版权保护．本文提出了一种基于混沌特性的DCT域的二值图像数字水印算法．该算法将含有版权信息的二值图像水印用混沌序列进行加密,把水印分量嵌入到不同图像块DCT中频系数中．通过加入高斯噪声、椒盐噪声以及JPEG压缩和剪切处理等大量试验,结果表明该算法具有很好的稳健性． 相似文献
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《常熟理工学院学报》2017,(4)
针对现有视频图像去雾存在信息丢失导致视频抖动的问题,提出了基于最小二乘法的B样条曲线的视频去雾方法 .首先,利用快速Harris角点检测提取视频关键帧的特征点;其次,对视频序列图像帧的特征点进行匹配;再次,基于最小二乘法利用关键帧像素点的估计非关键帧对应像素点的值点;最后,输出稳定完整的视频序列.实验结果表明,该算法利用曲线构建对特征点的处理能够有效地消除视频抖动现象. 相似文献
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关键帧提取技术是基于内容检索和视频分析的基础。关键帧的使用减少了视频索引的数据量,同时也为视频摘要和检索提供了一个组织框架。首先介绍了目前关键帧提取技术,然后提出了一种基于互信息量的关键帧提取方法,该算法以帧间互信息量来衡量两帧图像内容的相似性,可以对具体镜头按其特点自动提取出一个或多个关键帧。实验结果表明这种方法可以较好地概括视频内容。 相似文献
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提出了一种基于多小波变换的数字水印算法,将二值水印嵌入到宿主图像的多小波变换域中。首先将对应于相同位置的多小波系数形成向量序列,然后采用均值量化方法嵌入数字水印。实验结果表明,该水印算法在多种攻击下都具有较好的鲁棒性。 相似文献
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针对含水印视频受几何攻击的问题,提出基于小波变换与奇异值分解的视频数字水印算法。在探讨离散小波变换和奇异值分解概念的基础上,对已有算法进行分析,探讨其中存在的问题。提出基于小波变换与奇异值分解的视频数字水印算法,并探讨水印设计的思路、嵌入和提取框架图,完成仿真实验。最后,将本文算法与其它算法进行水印鲁棒性和不可见性比较。实验表明,该算法对几何攻击具有强鲁棒性。 相似文献
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针对数字图像版权保护的问题,设计了一种基于离散小波变换和图像分存的数字水印算法。算法将水印信息随机嵌入到图像的小波分解中频系数中,并且使用纠错编码和置乱加密,以增强算法的安全性。实验结果表明该算法是有效的。 相似文献
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Tayfun Tuna Jaspal Subhlok Lecia Barker Shishir Shah Olin Johnson Christopher Hovey 《Journal of Science Education and Technology》2017,26(1):82-99
Videos of classroom lectures have proven to be a popular and versatile learning resource. A key shortcoming of the lecture video format is accessing the content of interest hidden in a video. This work meets this challenge with an advanced video framework featuring topical indexing, search, and captioning (ICS videos). Standard optical character recognition (OCR) technology was enhanced with image transformations for extraction of text from video frames to support indexing and search. The images and text on video frames is analyzed to divide lecture videos into topical segments. The ICS video player integrates indexing, search, and captioning in video playback providing instant access to the content of interest. This video framework has been used by more than 70 courses in a variety of STEM disciplines and assessed by more than 4000 students. Results presented from the surveys demonstrate the value of the videos as a learning resource and the role played by videos in a students learning process. Survey results also establish the value of indexing and search features in a video platform for education. This paper reports on the development and evaluation of ICS videos framework and over 5 years of usage experience in several STEM courses. 相似文献
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Paul Van Mele Jonas Wanvoeke Cyriaque Akakpo Rosaline Maiga Dacko Mustapha Ceesay Louis Béavogui 《The Journal of Agricultural Education and Extension》2013,19(1):75-87
Abstract Will African farmers watch and learn from videos featuring farmers in Bangladesh? Learning videos on rice seed management were made with rural women in Bangladesh. By using a new approach, called zooming-in, zooming-out, the videos were of regional relevance and locally appropriate. When the Africa Rice Center (AfricaRice) introduced them to Africa in 2005, many scientists and civil servants thought that the videos would be culturally inappropriate and hence irrelevant to African smallholder farmers. However, African farmers who watched the videos did not experience cultural barriers. In fact, they enjoyed seeing another part of the world where farmers faced similar problems as theirs, and were able to solve these problems by themselves. To promote wider uptake of the videos a key challenge was to overcome the institutional barriers. Public sector agencies especially had to be convinced that African smallholders appreciated Asian videos. By watching the videos with farmers and listening to their feedback, the skeptical scientists and service providers changed their minds. By 2009, the Bangladeshi rice seed videos had been translated into 20 African languages and so became national products. Videos made according to the zooming-in zooming-out approach can bring farmer-to-farmer extension to a higher level of social aggregation. 相似文献
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Objective video quality assessment plays a very important role in multimedia signal processing. Several extensions of the structural similarity （SSIM） index could not predict the quality of the video sequence effectively. In this paper we propose a structural similarity quality metric for videos based on a spatial-temporal visual attention model. This model acquires the motion attended region and the distortion attended region by computing the motion features and the distortion contrast. It mimics the visual attention shifting between the two attended regions and takes the burst of error into account by introducing the non-linear weighting fimctions to give a much higher weighting factor to the extremely damaged frames. The proposed metric based on the model renders the final object quality rating of the whole video sequence and is validated using the 50 Hz video sequences of Video Quality Experts Group Phase I test database. 相似文献
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Gustav Bohlin Andreas Göransson Gunnar E. Höst Lena A. E. Tibell 《Science & Education》2017,26(7-9):975-999
Educational videos on the Internet comprise a vast and highly diverse source of information. Online search engines facilitate access to numerous videos claiming to explain natural selection, but little is known about the degree to which the video content match key evolutionary content identified as important in evolution education research. In this study, we therefore analyzed the content of 60 videos accessed through the Internet, using a criteria catalog with 38 operationalized variables derived from research literature. The variables were sorted into four categories: (a) key concepts (e.g. limited resources and inherited variation), (b) threshold concepts (abstract concepts with a transforming and integrative function), (c) misconceptions (e.g. that evolution is driven by need), and (d) organismal context (e.g. animal or plant). The results indicate that some concepts are frequently communicated, and certain taxa are commonly used to illustrate concepts, while others are seldom included. In addition, evolutionary phenomena at small temporal and spatial scales, such as subcellular processes, are rarely covered. Rather, the focus is on population-level events over time scales spanning years or longer. This is consistent with an observed lack of explanations regarding how randomly occurring mutations provide the basis for variation (and thus natural selection). The findings imply, among other things, that some components of natural selection warrant far more attention in biology teaching and science education research. 相似文献
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教学视频是线上课程的主要教学资源,也是实施翻转课堂、线上线下混合教学的关键要素。高质量的教学资源,是提升线上教学质量的前提。以31门国家级线上一流课程的116个教学视频作为样本,从技术指标、拍摄方法、视听要素和内容结构等方面总结视频制作规范。研究表明,合理使用新技术、新标准、新方法是制作高质量教学视频的保障;利用视听要素,提高教学内容的教学性和吸引力是制作高质量教学视频的关键;精心设计的教学环节是制作高质量教学视频的基础。 相似文献
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Adrian Simpson Naďa Vondrová Jana Žalská 《Journal of Mathematics Teacher Education》2018,21(6):607-630
A key requirement of successful initial teacher education is the development of professional vision, which includes shifting attention to features of the situation relevant to the specialized goals of teaching. Existing research hints at the value of targeted video-based courses in the development of professional vision, but often raises questions about the sources of shifts in the pattern of attention. We argue that existing work makes it difficult to distinguish whether shifts seen across video interventions are the results of the intervention, teaching experience, or methodological issues with the unbalanced use of videos in the data collection in these studies. Our first study suggests pre-service teachers’ teaching practice experience does not notably affect attention, but that choice of video does. Our second study addresses the methodological issues and suggests that we may discount different or unbalanced videos as a source of the shifts in the pattern of attention. Finally, by introducing a new synthesis of the results in the literature, we identify a previously hidden key distinction between studies and suggest reasons why different studies have shown different results in this area. 相似文献
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Prezi采用一张无限大的"画布"作为展示界面,可以嵌入文本、图像、视频等演示对象,利用缩放、平移和旋转的功效来创造非线性的演示效果。通过与Powerpoint的对比,凸显了Prezi在呈现海量信息、非连续性内容等方面的优势。并通过案例来具体说明Prezi可以很好的展示按照时空逻辑顺序、非线性关系、并列关系的教学内容;对于开放性问题的设置,和某些教学技巧的实现都具有强大的功能。最后强调了Prezi使用的注意事项。 相似文献
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In this quasi-experimental study, we describe the effect of showing dissection videos on first-year medical students' performance in terms of test scores during a gross anatomy course. We also surveyed students' perception regarding the showing of dissection videos. Two hundred eighty-seven first-year medical students at Rawalpindi Medical College in Pakistan, divided into two groups, dissected one limb in first term and switched over to the other limb in the second term. During the second term, instruction was supplemented by dissection videos. Second-term anatomy examination marks were compared with first-term scores and with results from first-year medical students in previous years. Multiple linear regression analysis was performed, with term scores (continuous, 0-200) as the dependent variable. Students shown dissection videos scored 1.26 marks higher than those not shown. The relationship was not statistically significant (95% CI: -1.11, 3.70; P = 0.314). Ninety-three percent of students favored regular inclusion of dissection videos in curriculum, and 50% termed it the best source for learning gross anatomy. Seventy-six percent of students did not perform regular cadaver dissection. The most frequent reason cited for not performing regular dissection was high student-cadaver ratio. Dissection videos did not improve performance on final examination scores; however, students favored their use. 相似文献