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1.
视网膜血管形态结构是反映人体健康的重要指标 ,针对现有视网膜血管分割存在主 血管模糊、微细血管断裂和视盘误分割等问题,提出多尺度特征融合双U型视网膜分割算 法。首先,利用低层U-Net高效循环残差模块对眼底图像进行粗粒度分割,得到视网膜血 管 初步轮廓。其次,将粗分割图与原始特征图像素相乘送入高层U-Net,利用其缩放宽残差 模 块进行细粒度图像解码,丰富视网膜血管细节信息。同时利用3路径注意力机制复合性连接 双网络的编码层与解码层,实现特征映射跨网络传播,减小上下文语义差异。最后,融合双 层网络输出提取血管区域,双U 型网络能够更深层次提取血管像素,精准分割出视网膜细 节。在DRIVE与STARE数据集上进行实验,其准确率分别为96.45%和97.02%,敏感度分 别为83.35%和81.40%,特异性分别为98.38%和 98.83%,总体性能优于现有算法。  相似文献   

2.
MS-UNet++:基于改进UNet++的视网膜血管分割   总被引:1,自引:0,他引:1  
本文针对视网膜图像中细微血管特征提取困难导致其分割难度高等问题,提出了一种 基于端到端的神经网络嵌套视网膜血管分割模型算法(简称MS-UNet++),该算法选取了深度监督网络UNet++作为分割网络模型,提升特征的使用效率;引入MulitRes模块,改善低对比度环境下细小血管的特征学习效果,并在特征提取后加上SENet模块进行挤压和激励操作,从而增强特征提取阶段的感受野,提高目标相关特征通道的权重。基于DRIVE图像数据集的实验结果表明,该算法分割结果与真实结果之间的重叠率DICE值为83.64%,并交比IOU为94.83%,准确度ACC为96.79%,灵敏度SE为81.78%,较现有模型有一定的提升,可用于视网膜图像血管分割,为临床诊断提供辅助信息。  相似文献   

3.
基于可控图像分割的快速视网膜血管提取算法   总被引:2,自引:2,他引:0  
针对多数视网膜血管提取算法实时性不强和分割 精度不高的问题,提出了一种基于可控图像分割的 快速视网膜血管提取算法。首先,对视网膜G分量图像的灰 度进行反转和自适应直方图均衡化,应用结 构元素为“菱形”和“圆盘形”的形态学“开”运算平滑图像背景和增强血管对比度,消除 视盘后阈值分割并二值 化得到不含视盘的分割图像。其次,根据在灰度图像中检测到的视盘构建掩膜,再次对 视网膜绿色分 量图像自适应直方图均衡化后进行阈值分割,并和掩膜进行逻辑“与”运算得到含有掩膜的 分割图像。最后, 将不含视盘的分割图像与含有掩膜的分割图像进行逻辑“与”运算,并融合边界信息获得最 终的视网膜血管 结构。实验结果表明,本文算法能有效提取视网膜眼底图像的血管网络,有较强的实时性和 较高的分割精度。  相似文献   

4.
视网膜血管的形态变化,如分叉角度、扩张程度等 ,可为眼底疾病的诊断提供依据。 使用深度学习技术对视网膜病变程度进行评估成为目前研究的重点。提出了一种基于多 路径输入和多尺度特征融合的视网膜血管分割方法来解决视网膜血管分割问题。采用了 多路径输入和多特征融合的方式改进了U-Net模型,使本文的网络能够有效的解决眼底视网 膜图像的分割效果差的 问题。实验结果表明,算法在DRIVE和CHASE_DB1数据集上,敏 感性分别取得0.814和0.813,特异性 分别取得0.984和0.986,在分割准确率指标上 分别取得0.969和0.975,所提方法相较于其他方法较优。  相似文献   

5.
针对视网膜图像血管细小,细节特征丢失、梯度下降、爆炸而导致分割效果差的问题,本文提出了一种引入残差块、循环卷积模块和空间通道挤压激励模块的U-Net视网膜血管图像分割模型。首先通过使用一系列随机增强来扩展训练集并对数据集进行预处理,然后在U-Net模型中引入残差块,避免随着网络深度增加,分割准确率达到饱和然后迅速退化以及优化计算成本;并将U-Net网络的底部替换为循环卷积模块,提取图像低层次的特征,并不断的进行特征积累,增强上下文之间的语义信息,获得更有效的分割模型;最后在卷积层之间嵌入空间通道挤压激励模块,通过找到特征较好的通道,强调这一通道,压缩不相关的通道使得网络模型能够加强关键语义特征信息的学习,通过训练过程学习到有效的特征信息,同时增强抗干扰能力。通过在DRIVE数据集上的验证结果可得,本文所提模型的准确率为98.42%,灵敏度达到了82.36%,特异值达到了98.86%。通过和其他网络分割方法比较,本文所提分割方法具有更优的分割效果。  相似文献   

6.
一种血管约束的局部活动轮廓模型   总被引:1,自引:1,他引:0       下载免费PDF全文
梁思  王雷  杨晓冬 《液晶与显示》2016,31(7):686-694
活动轮廓作为一种重要的图像分割工具,近几年来在理论和应用方面都有很大的发展。然而,现有轮廓模型在处理灰度均匀性较差的图像时,通常存在较高的分割误差,并且对初始轮廓曲线位置敏感。为此,本文提出一种基于血管特征约束的活动轮廓模型,该模型首先使用局部相位(Local Phase)的血管增强算法对图像进行增强处理以生成一种不同于图像灰度的血管特征信息,然后将血管信息和图像灰度以线性加权的形式引入到局部二值拟合(Local Binary Fitting,LBF)能量泛函中,指导图像血管分割。基于视网膜血管图像数据(Digital Retinal Images for Vessel Extraction,DRIV)的实验显示:该模型能成功地从灰度分布不均匀和弱边界轮廓的视网膜图像中提取血管,分割灵敏度和准确性分别达到74.43%和93.67%,同时对初始轮廓曲线位置的敏感性大为降低。由上述可知,该模型具有高分割准确性和低初始位置敏感性。  相似文献   

7.
基于视网膜血管模型的图像分割与血管提取   总被引:2,自引:0,他引:2  
本文采用非线性图像处理方法,对眼底图像进行去噪增强和分析,提取血管中心线,以便于对视网膜血管网络进行定量描述和定量分析。实验表明该方法能好地从非荧光眼底图像中提取出膜血管网络。  相似文献   

8.
一种基于改进的PCNN的视网膜血管树提取方法   总被引:2,自引:1,他引:1  
根据脉冲耦合神经网络(PCNN)动态点火特性和视网膜血管网络区域结构特征,提出了一种基于改进型PCNN(IPCNN)的视网膜血管树提取方法。该方法对二维高斯匹配滤波预处理增强后的眼底图像运用IPCNN分割出增强图像的血管网络,然后对分割得到的血管网络结合区域连通性特征,采用长度滤波算子滤除噪声,提取出最终的血管树。通过...  相似文献   

9.
基于过渡区提取的视网膜血管分割方法   总被引:2,自引:0,他引:2       下载免费PDF全文
姚畅  陈后金  李居朋 《电子学报》2008,36(5):974-978
 针对现有视网膜血管分割方法对于小血管和低对比度血管分割效果差的问题,提出了一种基于过渡区提取的视网膜血管分割方法.该方法首先采用二维高斯匹配滤波预处理以增强血管,然后采用基于最佳熵的方法提取主血管、采用基于分布式遗传算法和Otsu相结合的方法提取过渡区,最后利用区域连通性分析所提取的主血管和过渡区,分割出最终的血管.通过在Hoover眼底图像库中的实验,结果表明该方法在小血管的提取、连通性和有效性方面均优于Hoover算法,另外由于迁移策略的分布式遗传算法的引入,使得算法效率也明显提高.  相似文献   

10.
眼底图像中视网膜血管的结构对眼底疾病的分析和诊断具有重要的意义。针对匹配滤波方法中滤波参数的选取问题,文章提出了一种基于局部傅里叶变换的方向自适应匹配滤波的视网膜血管分割算法。文章算法首先对眼底图像进行预处理;通过分析预处理后的眼底图像中的局部傅里叶变换的能量分布,提取出血管点的主方向,同时利用Harris角点检测方法来校正血管分叉点的主方向;然后对每个像素点进行对应方向的匹配滤波;接着利用可变阈值方法对滤波后的图像进行分割;最后使用面积阈值法消除非血管点和噪声等。文章提出的算法对国际上公开的DRIVE库和STARE库进行了测试,实验结果证明了文中算法能够自适应地获取匹配滤波时的角度。  相似文献   

11.
High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET > PDMAT > TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.  相似文献   

12.
In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal (200) (2d = 0.4027 nm) is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line(w), the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line(x), the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines(y), the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line(z) in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line(q) in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution(λ/△ 2) is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.  相似文献   

13.
This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.  相似文献   

14.
An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.  相似文献   

15.
The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO>6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.  相似文献   

16.
This paper presents a brief overview of the Applied Centura(R)DPS(R)system,configured with silicon etch DPS Ⅱ chamber, with emphasis on discussing tuning capability for CD uniformity control. It also presents the studies of etch process chemistry and film integration impact for an overall successful gate patterning development. Discussions will focus on resolutions to key issues, such as CD uniformity, line-edge roughness, and multilayer film etching integration.  相似文献   

17.
We have fabricated the white organic light-emitting devices (WOLEDs) based on 4,4' -bis(2,2 -diphenyl vinyl)-1,1' - biphenyl (DPVBi) and phosphorescence sensitized 5,6,11,12,-tetraphenylnaphthacene (rubrene). The device structure is ITO/2T-NATA (20 nm)/NPBX (20 nm)/CBP: x%Ir(ppy)3:0.5% rubrene (8 nm)/NPBX (5 nm)/DPVBi (30 nm)/Alq(30 nm)/LiF(0.5 nm)/A1. In the devices, DPVBi acts as a blue light-emitting layer, the rubrene is sensitized by a phosphorescent material, fac tris (2-phenylpyridine) iridium [Ir(ppy)3], acts as a yellow light-emitting layer, and N,N' -bis- (1-naphthyl)- N,N' -diphenyl -1, 1' -biphenyl-4,4' -diamine (NPBX) acts as a hole transporting and exciton blocker layer, respectively. When the concentration of Ir (PPY)3 is 6wt%, the maximum luminance is 24960 cd/m^2 at an applied voltage of 15 V, and the maximum luminous efficiency is 5.17 cd/A at an applied voltage of 8 V.  相似文献   

18.
To meet the need of automatic image features extraction with high precision in visual inspection, a complete approach to automatic identification and sub-pixel center location for similar-ellipse feature is proposed. In the method, the feature area is identified automatically based on the edge attribute, and the sub-pixel center location is accomplished with the leastsquare algorithm. It shows that the method is valid, practical, and has high precision by experiment. Meanwhile this method can meet the need of instrumentation of visual inspection because of easy realization and without man-machine interaction.  相似文献   

19.
本论文提出一种在多天线MIMO信道相关性建模中小角度扩展近似理论算法,并应用于分析MIMO系统性能。分析中分别对三种不同角能量分布情况下的空间相关性研发快速近似计算法,并同时提出双模(Bi-Modal)角能量分布情况下的近似运算。通过分析这些新方法的近似效率,可以得到计算简单、复杂度低、而且符合实际的MIMO相关信道矩阵,对系统级的快速高效计算法的研究和系统级的评估以及误差分析具有重要的意义。  相似文献   

20.
We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.  相似文献   

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