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为提高对随机脉冲噪声(RVIN)图像的降噪效果,该文提出一种被称为双通道降噪卷积神经网络(D-DnCNN)的RVIN深度降噪模型。首先,提取多个不同阶对数差值排序(ROLD)统计值及1个边缘特征统计值构成描述图块中心像素点是否为RVIN噪声的噪声感知特征矢量。其次,利用预先训练好的深度置信网络(DBN)预测模型实现特征矢量到噪声标签的映射,完成对噪声图像中噪声点的检测。再次,在噪声检测标签的指示下采用Delaunay三角剖分插值算法快速修复噪声像素点从而获得初步复原图像。最后,将初步复原图像作为参考图像与噪声图像联接(concatenate)后输入D-DnCNN模型后获得残差图像,将参考图像减去残差图像即可获得降噪后图像。实验数据表明:D-DnCNN模型在各个噪声比例下的降噪效果均显著超过了现有的经典开关型RVIN降噪算法,与普通的单通道RVIN深度降噪模型相比也有较大幅度提升。 相似文献
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为提高现有随机脉冲噪声(RVIN)检测算法的检测准确率和执行效率,该文试图从构建描述能力更强的特征矢量和训练非线性映射更为准确的预测模型两个方面入手,实现一种基于训练策略的快速RVIN检测算法。一方面,提取多个不同阶的对数绝对差值排序统计值并结合一个能够反映图像边缘特性的统计值作为刻画图块中心像素点是否为噪声的特征矢量。在计算量增加极少的情况下,显著提升了特征矢量的描述能力。另一方面,基于深度置信网络(DBN)训练RVIN预测模型(RVIN检测器)将特征矢量映射为噪声类型标签,实现了比浅层预测模型更为准确的映射。大量实验数据表明:与现有的RVIN检测算法相比,所提算法在检测准确率和执行效率两个方面都更有优势。 相似文献
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针对Capon波束形成在误差条件下敏感性问题,提出一种基于协方差矩阵重构的鲁棒波束形成算法。算法将信号集中出现的空域划分为干扰区域和信号区域,接着将两个区域划分为若干相互独立不重叠的部分,对干扰区域积分,构造出干扰协方差矩阵;再利用采样协方差矩阵特征分解后的最小特征值重构出噪声协方差矩阵;最后对期望信号导向矢量误差进行环不确定集建模,并在期望信号导向矢量环不确定集上进行Capon谱积分来估计期望信号协方差矩阵,根据其主特征矢量获取期望信号导向矢量。仿真表明,与传统鲁棒波束形成算法相比,此方法在不同快拍数以及输入信噪比条件下,性能更加优异且稳定,同时计算量较小。 相似文献
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针对自适应波束形成器在目标导向矢量存在约束偏差时性能急剧下降的问题,该文提出一种目标导向矢量和干扰噪声协方差矩阵联合迭代估计的稳健波束形成算法。该算法首先采用稀疏重构的方法得到目标导向矢量的初始值,并通过从采样协方差矩阵中剔除目标信号估计值完成干扰加噪声协方差矩阵的初始化;然后在建立导向矢量误差优化模型的基础上,采用凸优化方法对目标导向矢量和干扰加噪声协方差矩阵联合迭代求解。最后利用目标导向矢量和干扰加噪声协方差矩阵的稳态估计值获得自适应权矢量。仿真结果表明该算法提高了波束形成器在目标导向矢量约束偏差时的输出信干噪比。 相似文献
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在实际应用环境中,信源和阵列传感器等存在误差,假设期望信号的导向矢量与真实信源导向矢量的失配会导致阵列波束形成器把期望信号当作干扰来加以抑制。针对信号匹配误差导致自适应波束形成性能下降的问题,提出了一种基于空时二维协方差矩阵修正的波束形成算法,利用空时结构对宽带幅相误差校正的特性,对空时二维协方差矩阵进行重构,并对修正协方差矩阵进行特征值分解,分离出信号加干扰子空间,将失配导向矢量投影可使期望信号与噪声子空间严格正交,最后求解算法最优权值。算法有效改善了波束形成的输出信噪比,计算机仿真验证了理论分析的正确性和算法的稳健性。 相似文献
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Application of convolutional neural networks (CNNs) for image additive white Gaussian noise (AWGN) removal has attracted considerable attentions with the rapid development of deep learning in recent years. However, the work of image multiplicative speckle noise removal is rarely done. Moreover, most of the existing speckle noise removal algorithms are based on traditional methods with human priori knowledge, which means that the parameters of the algorithms need to be set manually. Nowadays, deep learning methods show clear advantages on image feature extraction. Multiplicative speckle noise is very common in real life images, especially in medical images. In this paper, a novel neural network structure is proposed to recover noisy images with speckle noise. Our proposed method mainly consists of three subnetworks. One network is rough clean image estimate subnetwork. Another is subnetwork of noise estimation. The last one is an information fusion network based on U-Net and several convolutional layers. Different from the existing speckle denoising model based on the statistics of images, the proposed network model can handle speckle denoising of different noise levels with an end-to-end trainable model. Extensive experimental results on several test datasets clearly demonstrate the superior performance of our proposed network over state-of-the-arts in terms of quantitative metrics and visual quality. 相似文献
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基于视觉的非合作空间目标3维姿态估计,关键在于建立观测图像与目标模型的特征关联。当前方法往往通过采用复杂的多维特征、产生候选关联结果的方式确保特征关联的准确性,难以兼顾算法效率。为解决以上问题,该文提出一种结合深度学习技术的姿态估计方法,首先通过深度神经网络得到姿态初值,然后基于姿态初值建立图像和目标模型之间的特征关联,进而求解目标姿态。所提方法中,深度神经网络提供了稳定的姿态初值,缩小了特征关联的候选空间;在姿态初值的支撑下采取了更为高效的特征提取与匹配方法。仿真实验表明,该文方法相比于现有方法更好地兼顾了算法准确率和效率。 相似文献
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为了解决简单卷积神经网络(convolutional neural network, CNN)不能有效提取与充分利用高光谱图像特征信息的问题,提出了一种 基于残差网络的多层特征匹配生成对抗网络模型。提出的模型引入残差网络以挖掘高光谱图 像的深层特征,生成可分性更高的高光谱图像,并通过一个特征融合层进行特征融合,充分 利用网络的各层特征。提出的算法在Indian Pines、Pavia University和Salinas数据集 上的分类精度分别达到了97.6%,99.3%,99.1%,与径向基函数支持向量机(radial basis function-support vector machine, RBF-SVM)、堆叠自动编码器(stacked autoencoder, SAE)、深度置信网络(deep belief network, DBN)、PPF-CNN (CNN based on pixel-pair feature)、CNN和三维卷积网络 (three-dimensional convolutional neural network, 3D-CNN)方法相比较,其分类精度具有明显的提高。实验结果表明,提出的方法是一种有效 的高光谱图像分类方法。 相似文献
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Jie Li Jia Yan Dexiang Deng Wenxuan Shi Songfeng Deng 《Signal, Image and Video Processing》2017,11(6):985-992
The aim of research on the no-reference image quality assessment problem is to design models that can predict the quality of distorted images consistently with human visual perception. Due to the little prior knowledge of the images, it is still a difficult problem. This paper proposes a computational algorithm based on hybrid model to automatically extract vision perception features from raw image patches. Convolutional neural network (CNN) and support vector regression (SVR) are combined for this purpose. In the hybrid model, the CNN is trained as an efficient feature extractor, and the SVR performs as the regression operator. Extensive experiments demonstrate very competitive quality prediction performance of the proposed method. 相似文献
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Most existing convolutional neural network (CNN) based models designed for natural image quality assessment (IQA) employ image patches as training samples for data augmentation, and obtain final quality score by averaging all predicted scores of image patches. This brings two problems when applying these methods for screen content image (SCI) quality assessment. Firstly, SCI contains more complex content compared to natural image. As a result, qualities of SCI patches are different, and the subjective differential mean opinion score (DMOS) is not appropriate as qualities of all image patches. Secondly, the average score of image patches does not represent the quality of entire SCI since the human visual system (HVS) is sensitive to image patches containing texture and edge information. In this paper, we propose a novel quadratic optimized model based on the deep convolutional neural network (QODCNN) for full-reference (FR) and no-reference (NR) SCI quality assessment to overcome these two problems. The contribution of our algorithm can be concluded as follows: 1) Considering the characteristics of SCIs, a valid network architecture is designed for both NR and FR visual quality evaluation of SCIs, which makes the networks learn the feature differences for FR-IQA; 2) with the consideration of correlation between local quality and DMOS, a training data selection method is proposed to fine-tune the pre-trained model with valid SCI patches; 3) an adaptive pooling approach is employed to fuse patch quality to obtain image quality, owns strong noise robust and effects on both FR and NR IQA. Experimental results verify that our model outperforms both current no-reference and full-reference image quality assessment methods on the benchmark screen content image quality assessment database (SIQAD). Cross-database evaluation shows high generalization ability and high effectiveness of our model. 相似文献
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光响应非均匀性(photo-response non-uniformity,PRNU)是用于数字图像设备溯源的一种重要特征,也被称为成像设备指纹。针对图像真实噪声包含PRNU和大量未知噪声的复杂特性,本文提出一种结合深度迭代缩放卷积神经网络的PRNU数字成像设备指纹提取算法。首先,通过连续重复的缩小与放大特征图的分辨率来提高GPU内存利用效率和生成大的感受野,尽可能的提取包含完整PRNU指纹的真实噪声。然后,利用来自同一数字成像设备多幅图像的噪声残差来估计PRNU指纹。本文算法在相机溯源数据集Dresden和手机溯源数据集Daxing上进行了测试。实验结果显示,与传统方法相比本文算法具有的更好的识别率和普适性。 相似文献
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Liming Chen Cien Fan Haiyan Yang Shiyong Hu Lian Zou Dexiang Deng 《Signal, Image and Video Processing》2018,12(8):1531-1539
Face age estimation, a computer vision task facing numerous challenges due to its potential applications in identity authentication, human–computer interface, video retrieval and robot vision, has been attracting increasing attention. In recent years, the deep convolutional neural networks (DCNN) have achieved state-of-the-art performance in age classification of face images. We propose a deep hybrid framework for age classification by exploiting DCNN as the raw feature extractor along with several effective methods, including fine-tuning the DCNN into a fine-tuned deep age feature extraction (FDAFE) model, introducing a new method of feature extracting, applying the maximum joint probability classifier to age classification and a strategy to incorporate information from face images more effectively to improve estimation capabilities further. In addition, we pre-process the original image to represent age information more accurately. Based on the discriminative and compact framework, state-of-the-art performance on several face image data sets has been achieved in terms of classification accuracy. 相似文献
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针对小区间干扰导致蜂窝边缘无法满足不断增长的数据速率需求问题,毫米波无蜂窝大规模多输入多输出(Multiple-Input Multiple-Output, MIMO)系统被认为是一种很有前途的解决方案。然而,毫米波的高频率、大带宽以及接入点配置的大量天线给信道估计带来了较大挑战。将毫米波大规模MIMO信道矩阵视为二维图像,结合图像去噪方法提出一种基于改进去噪卷积神经网络(Improved-Denoising Convolutional Neural Network, I-DnCNN)的信道估计算法。通过具有注意力机制的压缩与激励(Squeeze-and-Excitation, SE)模块,自适应调整提取的全局特征以增强对信道噪声特征的学习,根据接收信号估计出噪声等级图且增添为输入,提升对噪声的鲁棒性。最后,采用残差学习的方式获得估计信道矩阵。利用理论信道模型和基于波束追踪的信道数据集进行的仿真实验结果表明,与去噪卷积神经网络(Denoising Convolutional Neural Network, DnCNN)算法相比,所提算法在两个数据集下的信道估计精度可分别平均提升2.27... 相似文献