共查询到20条相似文献,搜索用时 250 毫秒
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射线实时成像检测中的图像清晰度与分辨率 总被引:4,自引:0,他引:4
清晰度与分辨率是X射线实时成像检测中的重要质量特性,分析检测图像的清晰度与分辨率问题及相互关系,介绍分辨率测试卡结构和使用方法以及提高图像分辨率的途径。 相似文献
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在目前的主要数字射线成像检测技术标准中,关于源到工件表面距离都未作出正确、完整的规定。数字射线成像检测技术的检测图像不清晰度理论决定了需要依据检测图像不清晰度关系式,从可使用的放大倍数范围,同时规定源到工件表面距离和探测器位置。基于检测系统采用最佳放大倍数可获得最小的检测图像不清晰度,以工件中间层为基点,可作出简化处理。实例给出了简化处理的全部过程。 相似文献
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利用CCD摄像头,摄取了各种条件下的焊接坡口激光反射图像,其中包括夜间无其它照明光源图像、日光灯照明下的图像、室内自然光下的图像及阳光直射条件下的图像。试验结果表明,夜间无照明光源的图像具有较小的干扰,其它图像均存在较明显的相应照明光源的反射光干扰。通过加装窄带滤光片和适当的去噪预处理,可完全排除各种照明光源反射光的影响。采用复合形优化方法,提取出了坡口宽度、间隙宽度及间隙中心位置等信息,其误差绝对值不超过0.125mm,完全满足焊接跟踪的要求。 相似文献
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利用熔池图像表面的明暗变化恢复熔池表面三维形态,分析熔高和熔宽等特征与焊接质量的关系.试验装置采用红外激光辅助光源和带有近红外窄带滤波组合系统的高速影像设备实时捕捉熔池动态图像,并根据统计学估计光源位置参数,采用基于单幅熔池灰度图像的明暗恢复形状技术(shape from shading,SFS)中的局部分析算法来恢复熔池三维表面形态,并通过中值滤波和三次样条插值对三维重建后熔池形状进行去噪和平滑处理.结果表明,所采用的方法能有效地恢复熔池表面信息,为大功率盘形激光焊接过程中根据熔池二维图像预测焊缝成形提供了一种方法. 相似文献
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水下焊缝自动跟踪路径的识别 总被引:10,自引:3,他引:7
为满足水下焊缝自动跟踪的需要,设计了一个视觉系统。该系统采用卤钨灯作辅助光源照射焊接电弧前方一定距离处的待焊焊缝.配合复合滤光片进行滤光,能拍摄到较为清晰的焊缝图像。提出了一个基于边缘邻域平均值的算子,用于图像的边缘增强。运用改进的遗传算法计算图像类间方差,求出最佳阈值进行图像边缘分割,能较好地保留图像弱边缘.有效地减少计算时间。对分割后的焊缝图像,提出一种基于待焊焊缝宽度等特征的识别方法,能克服焊接弧光、飞溅、水流、气泡等干扰,识别水下待焊焊缝.准确地获取待焊焊缝中心线.为进一步实现水下焊接的自动化打下了基础。 相似文献
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《无损探伤》2018,(6)
在目前的主要数字射线成像检测技术标准中,关于DDA数字射线成像技术的源与工件源侧表面距离都未作出正确、完整的规定。常规胶片射线成像检测技术,基于在低能射线区胶片固有不清晰度很小,采用了几何不清晰度与胶片固有不清晰度匹配考虑作出规定,这时可以简单地对源与工件源侧表面最小距离作出限定。对于DDA数字射线成像检测技术,由于探测器固有不清晰度较大,不能按照匹配考虑简单规定源与工件源侧表面最小距离。从DDA数字射线成像检测技术实际的透照布置基本处理过程看到,需要的是考虑一次检验区、基于检测图像不清晰度公式,同时对源到工件源侧表面距离与探测器距离作出规定。基于最佳放大倍数可作出简化处理。 相似文献
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高速SMT生产线自动视觉检测系统 总被引:2,自引:0,他引:2
利用自动视觉检测系统,实现对高速SMT生产线贴片质量的在线检测,详细介绍了视觉检测系统的LED光源,分析了使用此光源的优点,提出用两种灯光,分两次扫描PCB板,得到两幅图像,以增加图像的信息量,减少误判。经出图像采集的具体措施和图像处理的常用算法,并给出了应用算法的具体实例,此系统具有开放性,可根据实际需要增加算法,进一步降低误判。 相似文献
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G. Agarwal H. Gao M. Amirthalingam M.J.M. Hermans 《Science & Technology of Welding & Joining》2018,23(2):134-139
In situ strain evolution during laser welding has been measured by means of digital image correlation to assess the susceptibility of an advanced high strength automotive steel to solidification cracking. A novel method realised using auxiliary illumination and optical narrow bandpass filter allowed strain measurements as close as 1.5?mm from the fusion boundary with good spatial and temporal resolution. A finite-element thermomechanical model of the welding process supports the experimentally measured transverse strain. The validated finite-element numerical model can be used to assess the local strain and associated stress conditions which influences weldability and in particular, solidification cracking. 相似文献
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鉴于以结构光为主动光源的焊缝跟踪方法可用于识别不同坡口形式的焊缝位置信息,对结构光焊缝图像进行了分析.为有效提取图像中结构光线性特征以确定焊缝位置,引入了束波变换.阐述了束波变换原理,开发了基于多尺度束波变换的结构光焊缝图像线性特征提取算法.做基于最大Beamlet统计的检验,对结构光焊缝图像进行小尺度束波变换以确定结构光线的大致位置,缩小搜索范围;然后对图像进行大尺度束波变换确定焊缝部分结构光线的线性特征,根据线段斜率变化可确定焊缝位置.采用该算法确定一幅结构光焊缝图像的焊缝位置的时间为260 ms. 相似文献
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This paper presents a method for identifying and precisely locating parts visible in the workspace of a robot workcell through analysis of single or multiple perspective images. Automatic integration of any number of arbitrary viewpoints permits detection of objects occluded from certain views, as well as providing varying image resolution and wider coverage of the visible workspace. Analysis is possible in the presence of image noise such as glare or shadow from poor lighting conditions, or structural errors such as missing or obscured object features. Automated visual detection of camera locations avoids precise camera positioning or setup time and permits use of a movable or roving camera. The system is capable of processing multiple camera input in a few seconds on a SUN 3/160 workstation, without the use of additional image processing hardware and can be easily ported to various computer systems. 相似文献
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Auto-detection of strip area in 3D measurement 总被引:5,自引:0,他引:5
3D measurement is an important task for modern manufacturing, because 2D measurement cannot meet the increasing requirements for quality control in engineering. Among all, 3D recovery methods, by using structural lighting system are the most popular methods because of its non-destructive character. The acquiring of lighting strips, which have to be projected on the object is the most important work to ensure later matching work. In the former research, the position of the stripes in the image was very difficult to locate and must be drawn manually. Therefore, the aim of our research is to find a method to auto-detect the strip area. FFT (fast Fourier transform algorithm) are used to analyze the image character by row and by column. From the FFT result, in the power spectrum the strip area and non-strip area can be distinguished clearly. So the strip area can be marked exactly on the image, and image process algorithm can be used to pick up the strips only on this area. After the matching and 3D recovery algorithm, the 3D shape of the object can be plotted. The auto-detection strip algorithm can save a lot of time for the 3D measurement, automatically complete the 3D recovery procedure, and bring convenience to operators. 相似文献
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为了达到自动控制光源、保障刀具柱面直接标刻二维条码识读的准确率高的目的,研究了二维条码识读系统中不同光源照明方式与照度对条码图像质量的影响规律,探明了图像质量与识读率的内在关系。通过实验,对不同照明方式下的图像质量评价系统进行了建模,并提出了一种评价图像质量的方法,即在组合照明方式下,以图像对比度为评价指标;在暗视场照明方式下,以图像低频分量比为评价指标,通过计算图像对比度和低频分量比是否达到一定阈值来评价图像质量,并以此控制光源照度,保证条码识读率在允许范围。 相似文献
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The computer evaluation of weld X-ray film is an attractive technique for weld seam NDT (nondestructive testing).To achieve this target,digitalization of film is the first step and automatic defect identification is another key techniqae.In this paper,a weld X-ray film digitalizing system has been established with linear array CCD and highlight LED light source.Its space resolution can reach 0.04 mm/pixel and scanning speed can reach 100 mm/s for an industrial film.The transfer function curves of the system have been measured and the results indicate that its image gray resolution can reach 88 G/D at 4.5D,and its dynamic range can be wider than 2.0D.In order to facilitate the evaluation of large welded structure,a panoramic evaluation algorithm is developed also.The algorithm includes image matching,image fusion and panoramic evaluation of the long linked film image. 相似文献