共查询到18条相似文献,搜索用时 125 毫秒
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目前,基于离散余弦变换的JPEG图像载体隐写已经可以达到较高的隐蔽性及鲁棒性,但隐写容量与传统的空域隐写相比仍有较大差距。在已有算法的基础上,提出了一种基于扩展DCT块变换的改进算法,一定程度上提升了隐藏容量,并使其在隐蔽性和展示性方面优于既有算法。该算法在最终量化前加入了扩展分块变换隐藏,避开了直接将密信隐藏于JPEG的量化后DCT系数中。在维持结果图片符合标准的同时,增强了隐写的隐蔽性和复杂性,实现了对原有算法的综合与改进。仿真实验结果显示出了该算法在隐写容量及隐秘性上相对于原有算法的提升。 相似文献
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目的:研究中国数字化女性虚拟人宫颈的剖面显示问题.方法:根据图像数据特点,从所获得的女性骨盆数据中提取出女性宫颈数据,然后通过计算机相邻两层图像之间像素对的相同程度来对其进行平移配准,最后利用C Builder语言编程实现剖面显示.结果:使用文中提及的方法对图像进行配准处理,我们发现在配准搜索过程中出现局部相似性最大的情况,从而使得搜索提前结束.结论:我们建议采用基于最大互信息量配准的方法,通过统计方法来表达图像像素的相似性特征,并利用优化算法有效克服局部极值,以便提高图像显示的精度,从而较好地应用于虚拟人体的其他部位的剖面显示. 相似文献
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提出了一种基于净图的多模纹理空域隐写分析方法。首先将图片进行切割并按照梯度能量划分成不同的集合;然后对这些集合中的图片用小波镜像滤波器恢复和进行LSB二次攻击,并提取三维净图特征向量;最后通过Oneclass SVM进行训练,得到多超球体SVM。该方法的优点是训练不需要载密图像,对空域隐写分析有很好的效果,在嵌入率为100%、50%、20%时,平滑组分别有100%、99.73%、66.22%的检出率,粗糙组分别有97.6%、72.6%、29.4%的检出率。 相似文献
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This paper focuses on the issue of extracting retina vessels with supervised approach. Since the green channel in the retina image has the best contrast between vessel and non-vessel, this channel is used to separate vessels. In our approach we are proposing a technique of using gray-level co-occurrence matrix method for composition of the retinal images. It is based on fact that the co-occurrence matrix of retina image describes the transition of intensities between neighbour pixels, indicating spatial structural information of retina image. So, we first extract the features vector based on specified characteristics of the gray-level co-occurrence matrix and then we use these features vector to train a neural network approach for the classification method which makes our proposed approach more effective. Obtained results from the experiments in DRIVE and STARE database shows the advantage of the proposed method in contrast to current methods. This advantage is evaluated by the criteria of sensitivity, specificity, area under ROC and accuracy. The result of such a conversion as the input vector of a multilayer perceptron neural network will be trained and tested. Although in recent years different methods have been presented in this respect, but results of simulation shows that the proposed algorithm has a very high efficiency than the other researches. 相似文献
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立体匹配通过计算和标识匹配图像的视差图来获得图像的深度信息,一般计算量大,无法满足实时性要求。本文聚焦立体匹配的匹配代价聚集和视差计算环节,在动态规划方法的基础上,提出了一种实时的立体匹配算法。根据连续性约束,提出了基于自适应形状窗口的快速匹配代价聚集算法,加速了臂长和匹配代价聚集的计算效率;利用边缘检测技术获得图像边界信息,修改动态规划的转移方程,使得边界像素可以在整个视差空间中选择视差值,降低边界处匹配视差的误匹配率。实验结果表明:通过结合上述两个步骤的改进算法,可以获得满足实时性要求、高质量的匹配视差图,整体的匹配准确率较高。 相似文献
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许莉莉 《中华医学杂志(英文版)》2013,126(9)
背景 眼底视网膜血管自动分割是基于眼底视网膜照片的计算机辅助诊断的首要课题。针对血管具有一定宽度的形态学特征,本文提出一种基于Sobel算子的眼底视网膜血管自动分割算法。
方法 在经过Sobel算子处理的眼底视网膜灰度梯度图像上,血管两侧边缘总是对应着沿水平方向或竖直方向相继出现的一对数值相当,符号相反的梯度谷-峰,这对梯度谷-峰之间的区域则被判断为血管像素。
结果 本文提出的方法采用公共DRIVE数据库中的眼底图像进行检测,检测结果显示平均灵敏度为 72.12% ,平均正确率为89.00%.
结论 本文提出的算法简单易实现,计算量小,能够提取视网膜上绝大部分血管。 相似文献
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Two-stage lossless data compression methods involving predictors and encoders are well known. This paper discusses the application of context based error modeling techniques for neural network predictors used for the compression of EEG signals. Error modeling improves the performance of a compression algorithm by removing the statistical redundancy that exists among the error signals after the prediction stage. In this paper experiments are carried out by using human EEG signals recorded under various physiological conditions to evaluate the effect of context based error modeling in the EEG compression. It is found that the compression efficiency of the neural network based predictive techniques is significantly improved by using the error modeling schemes. It is shown that the bits per sample required for EEG compression with error modeling and entropy coding lie in the range of 2.92 to 6.62 which indicates a saving of 0.3 to 0.7 bits compared to the compression scheme without error modeling. 相似文献
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针对人工识别汽车轮胎标识点颜色效率低、误差大的问题,研究了一种基于支持向量机的轮胎标识点颜色识别方法,利用PLC 工业相机图像采集系统获取轮胎标识点图像信息,对获取的标识点图像进行图像降噪、标识点分割、颜色特征向量提取等处理,将提取的轮胎标识点颜色特征向量输入到支持向量机颜色分类器中进行颜色识别。实验结果表明,该方法能够有效地识别出轮胎标识点颜色信息。 相似文献