structural similarity

结构相似性
  • 文章类型: Journal Article
    在使用无监督方法进行表面缺陷检测时,在重建高质量正常背景的同时准确检测缺陷仍然是一个重大挑战。本研究提出了一种无监督的方法,通过实现准确的缺陷检测和无噪声的高质量正常背景重建,有效地解决了这一挑战。我们提出了一种自适应加权结构相似性(AW-SSIM)损失用于聚焦特征学习。AW-SSIM通过为其亮度子函数分配不同的权重来改善结构相似性(SSIM)损失,对比,并根据它们对特定训练样本的相对重要性进行结构。此外,它在损耗计算期间动态调整高斯窗口的标准偏差(σ),以平衡降噪和细节保留。提出了一种人工缺陷生成算法(ADGA),以生成与真实缺陷非常相似的人工缺陷。我们采用两阶段训练策略。在第一阶段,该模型仅使用AW-SSIM损失对正常样本进行训练,允许它学习正常特征的鲁棒表示。在第二阶段的训练中,从第一阶段获得的权重用于在正常训练样本和人工缺陷训练样本上训练模型。此外,第二阶段采用组合学习的感知图像补丁相似度(LPIPS)和AW-SSIM损失。组合损失有助于模型实现高质量的正常背景重建,同时保持准确的缺陷检测。大量的实验结果表明,我们提出的方法达到了最先进的缺陷检测精度。所提出的方法在MVTec异常检测数据集中的六个样本上实现了97.69%的接收器工作特征曲线(AuROC)下的平均面积。
    Accurately detecting defects while reconstructing a high-quality normal background in surface defect detection using unsupervised methods remains a significant challenge. This study proposes an unsupervised method that effectively addresses this challenge by achieving both accurate defect detection and a high-quality normal background reconstruction without noise. We propose an adaptive weighted structural similarity (AW-SSIM) loss for focused feature learning. AW-SSIM improves structural similarity (SSIM) loss by assigning different weights to its sub-functions of luminance, contrast, and structure based on their relative importance for a specific training sample. Moreover, it dynamically adjusts the Gaussian window\'s standard deviation (σ) during loss calculation to balance noise reduction and detail preservation. An artificial defect generation algorithm (ADGA) is proposed to generate an artificial defect closely resembling real ones. We use a two-stage training strategy. In the first stage, the model trains only on normal samples using AW-SSIM loss, allowing it to learn robust representations of normal features. In the second stage of training, the weights obtained from the first stage are used to train the model on both normal and artificially defective training samples. Additionally, the second stage employs a combined learned Perceptual Image Patch Similarity (LPIPS) and AW-SSIM loss. The combined loss helps the model in achieving high-quality normal background reconstruction while maintaining accurate defect detection. Extensive experimental results demonstrate that our proposed method achieves a state-of-the-art defect detection accuracy. The proposed method achieved an average area under the receiver operating characteristic curve (AuROC) of 97.69% on six samples from the MVTec anomaly detection dataset.
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  • 文章类型: Journal Article
    背景:图像配准在许多临床任务中是一个具有挑战性的问题,但是在过去的几年中,深度学习在这一领域取得了重大进展。通过监督变换估计,可以实现实时和鲁棒的配准。然而,使用此框架的注册质量取决于诸如位移场之类的地面实况标签的质量。
    目的:提出一种简单可靠的方法,用于以完全无监督的方式基于图像结构相似性配准医学图像。
    方法:我们提出了一种深度级联无监督可变形配准方法,用于在没有可靠临床数据标签的情况下对齐图像。我们的基本网络由位移估计模块(ResUnet)和变形模块(空间变换器层)组成。我们采用l2$l_2$范数正则化变形场,而不是传统的l1$l_1$范数正则化。此外,我们在训练阶段利用结构相似性(ssim)估计来增强变形图像和参考图像之间的结构一致性。
    结果:实验结果表明,通过结合ssim损失,我们的级联方法不仅在CT图像上获得了更高的骰子得分0.9873,ssim得分0.9559,归一化互相关(NCC)得分0.9950和更低的相对平方差总和(SSD)误差0.0313,但也优于超声数据集上的比较方法。统计t$t$检验结果也证明了我们方法的这些改进具有统计学意义。
    结论:在这项研究中,基于不同评估指标的有希望的结果表明,我们的模型在可变形图像配准(DIR)中简单有效。通过肝脏CT图像和心脏超声图像的实验验证了模型的泛化能力。
    BACKGROUND: Image registration is a challenging problem in many clinical tasks, but deep learning has made significant progress in this area over the past few years. Real-time and robust registration has been made possible by supervised transformation estimation. However, the quality of registrations using this framework depends on the quality of ground truth labels such as displacement field.
    OBJECTIVE: To propose a simple and reliable method for registering medical images based on image structure similarity in a completely unsupervised manner.
    METHODS: We proposed a deep cascade unsupervised deformable registration approach to align images without reliable clinical data labels. Our basic network was composed of a displacement estimation module (ResUnet) and a deformation module (spatial transformer layers). We adopted l 2 $l_2$ -norm to regularize the deformation field instead of the traditional l 1 $l_1$ -norm regularization. Additionally, we utilized structural similarity (ssim) estimation during the training stage to enhance the structural consistency between the deformed images and the reference images.
    RESULTS: Experiments results indicated that by incorporating ssim loss, our cascaded methods not only achieved higher dice score of 0.9873, ssim score of 0.9559, normalized cross-correlation (NCC) score of 0.9950, and lower relative sum of squared difference (SSD) error of 0.0313 on CT images, but also outperformed the comparative methods on ultrasound dataset. The statistical t $t$ -test results also proved that these improvements of our method have statistical significance.
    CONCLUSIONS: In this study, the promising results based on diverse evaluation metrics have demonstrated that our model is simple and effective in deformable image registration (DIR). The generalization ability of the model was also verified through experiments on liver CT images and cardiac ultrasound images.
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  • 文章类型: Journal Article
    红外(IR)小目标检测,尤其是在复杂的背景下,在低误报率和高鲁棒性方面继续面临挑战。在本文中,提出了一种背景减除局部对比度度量(BSLCM)和高斯结构相似性(GSS)集成的结构模型来检测红外小目标。在提出的模型中,BSLCM用于抑制复杂背景并增强目标。进行GSS计算以进一步消除高亮的背景残差和噪声。为了评估所提出方法的性能,采用了真实的红外序列和七种最先进的(SOTA)方法。结果表明,BSLCM可以有效抑制各种强背景杂波,增强真实目标。
    Infrared (IR) small target detection, especially in a complex background, continues to present challenges in the low false alarm rate and high robustness. In this paper, a background subtraction local contrast measure (BSLCM) and Gaussian structural similarity (GSS) integrated structural model is proposed to detect IR small target. In the proposed model, BSLCM is used to suppress the complex background and enhance the target. GSS calculation is conducted to eliminate the high-brightened background residual and noise further. To evaluate the performance of the proposed method, real IR sequences and seven state-of-the-art (SOTA) methods were adopted. The results demonstrated that the BSLCM can suppress all types of strong background clutter and enhance the true target effectively.
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  • 文章类型: Journal Article
    延迟容忍网络(DTN),其特点是难以建立端到端路径和较大的消息传播延迟。为了控制网络间接费用,减少消息延迟,并提高DTN的交付率,重要的是,不仅要删除已到达目的地的消息,还要更精确地确定适当的中继节点。基于上述目标,借鉴社区划分(QLCR)的思想,构建了基于Q-lambda强化学习的多副本中继节点选择路由器算法。在社区划分中,如果一个节点具有最高的学位,它被认为是核心节点,将具有相似兴趣和结构属性的节点划分为一个社区。节点度是指与节点关联的节点数,说明其在网络中的重要性。结构相似性决定了节点之间的距离。中继节点的选择考虑节点度,利益,结构相似性。Q-lambda强化学习算法使每个节点能够从整个网络中学习,根据遇到的满足指定条件的节点设置相应的奖励值。通过迭代过程,选择累积奖励值最大的节点作为最终中继节点。实验结果表明,该算法在保持较低的网络开销和时延的同时,实现了较高的传输速率。
    Delay tolerant networks (DTNs), are characterized by their difficulty in establishing end-to-end paths and and large message propagation delays. To control network overhead costs, reduce message delays, and improve delivery rates in DTNs, it is essential to not only delete messages that have reached their destination but also to more precisely determine appropriate relay nodes. Based on the above goals, this paper constructs a multi-copy relay node selection router algorithm based on Q-lambda reinforcement learning with reference to the idea of community division (QLCR). In community division, if a node has the highestdegree, it is considered the core node, and nodes with similar interests and structural properties are divided into a community. Node degree refers to the number of nodes associated with the node, indicating its importance in the network. Structural similarity determines the distance between nodes. The selection of relay nodes considers node degree, interests, and structural similarity. The Q-lambda reinforcement learning algorithm enables each node to learn from the entire network, setting corresponding reward values based on encountered nodes meeting the specified conditions. Through iterative processes, the node with the most cumulative reward value is chosen as the final relay node. Experimental results demonstrate that the proposed algorithm achieves a high delivery rate while maintaining low network overhead and delay.
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  • 文章类型: Journal Article
    背景:大量研究表明,环状RNA(circularRNA)通过竞争性结合miRNA来影响生物过程,为诊断提供了新的视角,和治疗人类疾病。因此,探索潜在的circRNA-miRNA相互作用(CMIs)是目前一项重要而紧迫的任务。尽管已经尝试了一些计算方法,它们的性能受到稀疏网络中特征提取的不完整性和冗长数据的低计算效率的限制。
    结果:在本文中,我们提出了JSNDCMI,结合了多结构特征提取框架和去噪自动编码器(DAE),以应对稀疏网络中CMI预测的挑战。详细来说,JSNDCMI通过多结构特征提取框架将功能相似度和局部拓扑结构相似度集成在CMI网络中,然后强制神经网络通过DAE学习特征的鲁棒表示,最后使用梯度提升决策树分类器来预测潜在的CMI。JSNDCMI在所有数据集的5倍交叉验证中产生最佳性能。在案例研究中,得分最高的前10名CMI中有7名在PubMed中进行了验证。
    背景:数据和源代码可以在https://github.com/1axin/JSNDCMI找到。
    A large number of studies have shown that circular RNA (circRNA) affects biological processes by competitively binding miRNA, providing a new perspective for the diagnosis, and treatment of human diseases. Therefore, exploring the potential circRNA-miRNA interactions (CMIs) is an important and urgent task at present. Although some computational methods have been tried, their performance is limited by the incompleteness of feature extraction in sparse networks and the low computational efficiency of lengthy data.
    In this paper, we proposed JSNDCMI, which combines the multi-structure feature extraction framework and Denoising Autoencoder (DAE) to meet the challenge of CMI prediction in sparse networks. In detail, JSNDCMI integrates functional similarity and local topological structure similarity in the CMI network through the multi-structure feature extraction framework, then forces the neural network to learn the robust representation of features through DAE and finally uses the Gradient Boosting Decision Tree classifier to predict the potential CMIs. JSNDCMI produces the best performance in the 5-fold cross-validation of all data sets. In the case study, seven of the top 10 CMIs with the highest score were verified in PubMed.
    The data and source code can be found at https://github.com/1axin/JSNDCMI.
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  • 文章类型: Journal Article
    UNASSIGNED:PET代谢图像和CT解剖图像的融合可以同时显示代谢活动和解剖位置,对肺癌的分期诊断和准确定位起着不可或缺的作用。
    UNASSIGNED:为了提高PET-CT融合图像的信息,本文提出了一种基于暹罗金字塔融合网络(SPFN)的PET-CT融合方法。在这种方法中,将特征金字塔变换引入到Siamese卷积神经网络中提取图像的多尺度信息。在目标函数的设计中,本文考虑了图像融合问题的本质,利用图像结构相似度作为目标函数,引入L1正则化以提高图像质量。
    UNASSIGNED:通过700多对PET-CT图像和精心的实验设计,验证了所提出方法的有效性。融合后的视觉保真度达到0.350,信息熵达到0.076。
    UNASSIGNED:定量和定性结果证明,所提出的PET-CT融合方法具有一些优点。此外,结果表明,与单模态图像相比,PET-CT融合图像可以提高分期诊断能力。
    UNASSIGNED: The fusion of PET metabolic images and CT anatomical images can simultaneously display the metabolic activity and anatomical position, which plays an indispensable role in the staging diagnosis and accurate positioning of lung cancer.
    UNASSIGNED: In order to improve the information of PET-CT fusion image, this article proposes a PET-CT fusion method via Siamese Pyramid Fusion Network (SPFN). In this method, feature pyramid transformation is introduced to the siamese convolution neural network to extract multi-scale information of the image. In the design of the objective function, this article considers the nature of image fusion problem, utilizes the image structure similarity as the objective function and introduces L1 regularization to improve the quality of the image.
    UNASSIGNED: The effectiveness of the proposed method is verified by more than 700 pairs of PET-CT images and elaborate experimental design. The visual fidelity after fusion reaches 0.350, the information entropy reaches 0.076.
    UNASSIGNED: The quantitative and qualitative results proved that the proposed PET-CT fusion method has some advantages. In addition, the results show that PET-CT fusion image can improve the ability of staging diagnosis compared with single modal image.
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  • 文章类型: Journal Article
    细菌感染是影响人类寿命的重要因素之一。老年人由于免疫力不足而受到细菌感染的伤害更大。由于近年来缺乏新的抗生素,细菌耐药性已日益成为全球性的严重问题。在这项研究中,使用支持向量机和随机森林方法以及ChEMBL数据库中活性和非活性抗菌化合物的数据构建抗菌化合物预测因子.结果表明,两种模型均具有出色的预测性能(两种模型的平均精度>0.9,平均AUC>0.9)。我们使用预测因子从DrugBank数据库中的FDA批准的药物中筛选潜在的抗菌化合物。筛选结果显示,1087种小分子药物具有潜在抗菌活性,其中154种为FDA批准的抗菌药物,占本研究中已批准的抗菌药物的76.2%。通过分子指纹图谱相似性分析和常见子结构分析,我们筛选了8个与已知抗菌药物相比具有新结构的预测抗菌小分子化合物,其中5种广泛应用于各种肿瘤的治疗。这项研究为使用批准的药物预测抗菌化合物提供了新的见解,预测的化合物可能用于治疗细菌感染和延长寿命。
    Bacterial infection is one of the most important factors affecting the human life span. Elderly people are more harmed by bacterial infections due to their deficits in immunity. Because of the lack of new antibiotics in recent years, bacterial resistance has increasingly become a serious problem globally. In this study, an antibacterial compound predictor was constructed using the support vector machines and random forest methods and the data of the active and inactive antibacterial compounds from the ChEMBL database. The results showed that both models have excellent prediction performance (mean accuracy >0.9 and mean AUC >0.9 for the two models). We used the predictor to screen potential antibacterial compounds from FDA-approved drugs in the DrugBank database. The screening results showed that 1087 small-molecule drugs have potential antibacterial activity and 154 of them are FDA-approved antibacterial drugs, which accounts for 76.2% of the approved antibacterial drugs collected in this study. Through molecular fingerprint similarity analysis and common substructure analysis, we screened 8 predicted antibacterial small-molecule compounds with novel structures compared with known antibacterial drugs, and 5 of them are widely used in the treatment of various tumors. This study provides a new insight for predicting antibacterial compounds by using approved drugs, the predicted compounds might be used to treat bacterial infections and extend lifespan.
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  • 文章类型: Journal Article
    Protein design has become a powerful method to expand the number of natural proteins and design customized proteins according to demands. Domain-based protein design spares the need to create novel elements from scratch, which makes it a more efficient strategy than scratch-based protein design in designing multi-domain proteins, protein complexes and biomaterials. As the surface shape plays a central role in domain-domain and protein-protein interactions, a global map of the surface shapes of all domains should be very beneficial for domain-based protein design. Therefore, in this study, we characterized the surface shapes of protein domains, collected from CATH and SCOP databases, with their 3D-Zernike descriptors (3DZDs). Then similarities of domain shape features were identified, and all domains were classified accordingly. The preferences of the combinations of domains between different clusters were analyzed in natural proteins from the Protein Data Bank. A user-friendly website, termed CPD3DS, was also developed for storage, retrieval, analyses and visualization of our results. This work not only provides an overall view of protein domain shapes by showing their variety and similarities, but also opens up a new avenue to understand the properties of protein structural domains, and design principles of protein architectures.
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  • 文章类型: Journal Article
    在复合凝聚之前,采用两步乳化来开发亲水性和疏水性成分的共包封技术,以增强营养。评估了以明胶和羧甲基纤维素钠为壁材的单核椭圆形微胶囊的加工参数。水-油相比和总生物聚合物浓度显著影响微胶囊的粒径和形态以及L-抗坏血酸的包封率。L-抗坏血酸和槲皮素共包封的微胶囊的平均尺寸为65.26µm,显示出良好的物理和化学稳定性。L-抗坏血酸和槲皮素的包封率分别为69.91%和88.21%,分别。为了预测功能性脂质作为疏水载体的潜力,使用大豆油的微胶囊,橄榄油,鱼油,并开发了共轭亚油酸作为层间油。不同油携带的疏水化合物的包封效率同样高(88.21-93.08%),然而,共轭亚油酸携带的亲水性包封率最低(32.54%)。界面张力结果表明,共轭亚油酸与疏水乳化剂在界面上的竞争关系损害了界面稳定性,由于它们的结构相似性。这些结果为提高微胶囊夹层油的质量提供了指导。
    A two-step emulsification prior to complex coacervation was employed to develop a co-encapsulation technology of hydrophilic and hydrophobic components for nutrition enhancement. Processing parameters of mononuclear ellipse-like microcapsules using gelatin and sodium carboxymethyl cellulose as wall materials were evaluated. The particle size and morphology of microcapsules and the encapsulation efficiency of L-ascorbic acid were significantly affected by the water-oil phase ratio and total biopolymer concentration. The L-ascorbic acid and quercetin co-encapsulated microcapsules with an average size of 65.26 µm showed good physical and chemical stability. The encapsulation efficiencies of L-ascorbic acid and quercetin were 69.91% and 88.21%, respectively. To predict the potential of functional lipids as hydrophobic carriers, microcapsules using soybean oil, olive oil, fish oil, and conjugated linoleic acid as interlayer oils were developed. The encapsulation efficiencies of hydrophobic compounds carried by different oils were similarly high (88.21-93.08%), whereas, hydrophilic ones carried by conjugated linoleic acid had the lowest encapsulation efficiency (32.54%). The interface tension results indicated that the interfacial stability was impaired by a competitive relation between conjugated linoleic acid and hydrophobic emulsifier at the interface, due to their structural similarity. These results provided the guidance for improving the quality of interlayer oils from microcapsules.
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  • 文章类型: Journal Article
    卷积神经网络最近已用于多焦点图像融合。然而,一些现有的方法已经采取了将高斯模糊添加到聚焦图像中,为了模拟散焦,从而生成用于监督学习的数据(具有地面实况)。此外,他们将像素分类为“聚焦”或“散焦”,并利用分类结果构建融合权重图。这就需要一系列的后处理步骤。在本文中,我们提出了一种端到端的学习方法,用于从多焦点输入图像对中直接预测完全聚焦的输出图像。建议的方法使用经过训练的CNN架构来执行融合,不需要地面真相融合图像。CNN利用图像结构相似性(SSIM)来计算损失,一种被广泛接受的用于融合图像质量评估的度量标准。更重要的是,在设计损失函数时,我们还使用图像局部窗口的标准偏差来自动估计源图像在最终融合图像中的重要性。我们的网络可以接受可变大小的图像,因此,我们能够利用真实的基准数据集,而不是模拟的,训练我们的网络。该模型是前馈,完全卷积神经网络,可以在测试时间内处理可变大小的图像。对基准数据集的广泛评估表明,我们的方法优于,或者与,现有的最先进的技术在客观和主观的基准。
    Convolutional neural networks have recently been used for multi-focus image fusion. However, some existing methods have resorted to adding Gaussian blur to focused images, to simulate defocus, thereby generating data (with ground-truth) for supervised learning. Moreover, they classify pixels as \'focused\' or \'defocused\', and use the classified results to construct the fusion weight maps. This then necessitates a series of post-processing steps. In this paper, we present an end-to-end learning approach for directly predicting the fully focused output image from multi-focus input image pairs. The suggested approach uses a CNN architecture trained to perform fusion, without the need for ground truth fused images. The CNN exploits the image structural similarity (SSIM) to calculate the loss, a metric that is widely accepted for fused image quality evaluation. What is more, we also use the standard deviation of a local window of the image to automatically estimate the importance of the source images in the final fused image when designing the loss function. Our network can accept images of variable sizes and hence, we are able to utilize real benchmark datasets, instead of simulated ones, to train our network. The model is a feed-forward, fully convolutional neural network that can process images of variable sizes during test time. Extensive evaluation on benchmark datasets show that our method outperforms, or is comparable with, existing state-of-the-art techniques on both objective and subjective benchmarks.
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