基于高频能量参数Eh的微操作纵向深度估计

提出了利用散焦图像的高频能量参数获取深度信息的新方法．算法实现步骤分为两步：首先通过标定实验，从一组在2μm间隔深度下采集的微工具序列模糊图像中导出深度计算方程，然后，在实际深度估计中，测得深度对应的能量参数，代入深度方程，求解出深度值．在测试实验中，讨论并解决了微工具形状不均对标定实验的影响．该技术已经成功地应用到NKTY-MR系列微操作机器人系统，准确快捷地完成了深度估计和自动调焦的操作．     

单微粒三维纳米级实时定位算法的研究

单微粒定位技术为研究纳米微粒的动力学特性提供了重要手段。文章通过研究纳米微粒的离焦图像,分析计算出离焦图像与离焦距离的关系。由此开发出单微粒三维纳米级实时定位算法,为研究复杂环境中纳米微粒的动力学特性提供了有效地研究手段。     

An efficient projection defocus algorithm based on multi-scale convolution kernel templates

The focal problems of projection include out-of-focus projection images from the projector caused by incomplete mechanical focus and screen-door effects produced by projection pixilation. To eliminate these defects and enhance the imaging quality and clarity of projectors, a novel adaptive projection defocus algorithm is proposed based on multi-scale convolution kernel templates. This algorithm applies the improved Sobel-Tenengrad focus evaluation function to calculate the sharpness degree of intensity equalization and then constructs multi-scale defocus convolution kernels to remap and render the defocus projection image. The resulting projection defocus corrected images can eliminate out-of-focus effects and improve the sharpness of uncorrected images. Experiments show that the algorithm works quickly and robustly and that it not only effectively eliminates visual artifacts and can run on a self-designed smart projection system in real time but also significantly improves the resolution and clarity of the observer＇s visual perception.     

Defocus deblurring for catadioptric omnidirectional imaging based on coded aperture and omni-total variation

The problem of catadioptric omnidirectional imaging defocus blur, which is caused by lens aperture and mirror curvature, becomes more severe when high-resolution sensors and large apertures are applied. In order to overcome this problem, a novel method based on coded aperture technique is proposed in this article. Firstly, the defocus blur of catadioptric omnidirectional imaging is analyzed to calculate the point spread function for different scene points. Then, a method of obtaining optimal focused plane is proposed. Lastly, based on the strategies of neighboring annuluses division and stitching of omnidirectional images, a deconvolution algorithm using omni-total variation prior is applied to obtain all-focused/sharp omnidirectional images. Experimental results demonstrate that the proposed method is effective for omnidirectional image defocus deblurring and can be applied to most existing catadioptric omnidirectional imaging systems.     

一种基于边缘扩散函数描述散焦程度的测距算法

基于散焦图像的景物距离信息获取是当前计算机视觉研究的热门课题,但当前多数方法存在有一定的局限性,无法满足现代高效率工业检测技术的要求.本文提出一种散焦测距的新方法,该方法利用调制传递函数(MTF)来描述图像的散焦程度,通过对测量系统进行标定得到物距与散焦程度之间的关系曲线,再求得被测物在未知物距上的MTF值,根据对系统...     

融合两种深度线索的光场图像深度估计方法

针对传统的光场深度估计算法采用单一的深度线索进行深度估计,导致估计结果精度较低的问题,,提出了一种融合视差和散焦量两种深度线索的光场深度估计的方法。该方法首先进行深度线索的构建,将输入的光场图片转化为EPI Volume和Refocus Volume结构,通过卷积神经网络将EPI特征和散焦特征转化为深度信息,为了克服训练数据不足,采用色彩变换、缩放和随机灰度化等方式进行数据扩容。最终在HCI 4D光场标准数据集上的对比测试结果表明,该方法在均方误差和坏像素率上优于传统算法,且在执行时间上也具有很大优势。     

单幅自然场景深度恢复

离焦测距算法是一种用于恢复场景深度信息的常用算法。传统的离焦测距算法通常需要采集多幅离焦图像,实际应用中具有很大的制约性。文中基于局部模糊估计提出单幅离焦图像深度恢复算法。基于局部模糊一致性的假设,本文采用简单而有效的两步法恢复输入图像的深度信息：1)通过求取输入离焦图和利用已知高斯核再次模糊图之间的梯度比得到边缘处稀疏模糊图 2)将边缘位置模糊值扩离至全部图像,完整的相对深度信息即可恢复。为了获得准确的场景深度信息,本文加入几何条件约束、天空区域提取策略来消除颜色、纹理以及焦点平面歧义性带来的影响,文中对各种类型的图片进行对比实验,结果表明该算法能在恢复深度信息的同时有效抑制图像中的歧义性。     

皮肤镜图像散焦模糊与光照不均混叠时的无参考质量评价

皮肤镜图像的采集质量直接影响后续的分析诊断结果.针对皮肤镜图像在采集过程中可能出现的散焦模糊和光 照不均两种类型的失真,提出了一种有效的无参考图像质量评价算法. 通过频率特性分析我们发现,散焦模糊主要 影响离散余弦变换（Discrete cosine transform,DCT）后的直流分量,而光照不均则主要影响第一交流分量.针对该特性,论文在频率域设计质量评价模型,首先将散焦模糊与光照不均两种失真成功分离,进而分别计算失真程度,给出评价指标.实验结 果表明,本文提出的算法既可以对散焦模糊或光照不均单一失真类型的皮肤镜图像进行质量评价,也可以对两种失真类型 同时存在的复杂皮肤图像进行评价,给出的评价结果稳定客观、互相独立,且与主观评价结果相一致.     

散焦和运动模糊复合模型及参数估计

为了解决散焦和运动模糊同时存在的图像复原问题,建立了一种散焦和运动模糊复合模型,提出了一种基于自相关的参数估计方法.在分析图像成像过程的基础上,对标准散焦模型和运动模糊模型进行卷积,估计复合模型的分布范围,根据光的散射特性和能量守恒调整复合模糊模型的幅度.对复合模型按两方向分别求导,根据导数矩阵自相关的曲线特性估计模糊参数.实验结果表明,参数估计方法具有较高的估计精度,解决了混叠现象造成的干扰问题,复合模型则能够取得较好的复原效果.     

Impact of the pupil size – central optical zone diameter relationship on visual performance in aspheric multifocal contact lenses

PurposeTo determine the impact of different central optical zone diameters (COZDs), obtained from pupil size, on the visual performance of presbyopic subjects fitted with centre-distance simultaneous-image multifocal contact lenses (SIMCLs).MethodsThirty-two presbyopic volunteers, between 45–58 years of age, participated in this prospective, controlled, double-blind study. Subjects were fitted with 5 centre-distance SIMCLs of variable COZD, determined from the measurement of pupil size under photopic light conditions and corresponding to 60, 70, 80, 90 and 100 % of pupil diameter. Subjects visual performance was evaluated through the measurement of distance, intermediate and near visual acuity (VA), “visual functional range” (VFR) obtained from the VA Defocus Curve (VADC) and Contrast Sensitivity Function (CSF), using a third-generation retina display iPad.ResultsStatistically significant differences were obtained for both distance (p = 0.01) and intermediate (p = 0.001) VA amongst designs. Best results were obtained with 80 % and 90 % COZDs compared to 60 %. No significant differences in VFR (p > 0.05) were obtained amongst the different COZDs. 90 and 100 % COZDs offered statistically significant better results at 6 and 18 cycles per degree (cpd) in the CSF, compared to the 60 and 70 % designs.ConclusionsSIMCLs with COZDs of 80–90 % and of 90–100% of photopic pupil diameter offered better distance and intermediate VA, without a decline in near performance, and superior contrast sensitivity at medium and high spatial frequencies respectively, compared to lower COZD designs.