Image editing in the contour domain

We propose a novel method for image editing in which the primitive working unit is not a pixel but an edge. The feasibility of this proposal is suggested by the recent work of Elder et al. (1998) showing that a gray-scale image can be accurately represented by its edge map if a suitable edge model and scale selection method are employed. In particular, an efficient algorithm has been reported by Elder et al. (1996) and Elder (1999) to invert such an edge representation to yield a high-fidelity reconstruction of the original image. We combined these algorithms together with an efficient method for contour grouping and an intuitive user interface to allow users to perform image editing operations directly in the contour domain. Experimental results suggest that this novel combination of vision algorithms may increase the efficiency of certain classes of image editing operations     

Videoshop: A new framework for spatio-temporal video editing in gradient domain

This paper proposes a new framework for video editing in gradient domain. The spatio-temporal gradient fields of target videos are modified and/or mixed to generate a new gradient field which is usually not integrable. We compare two methods to solve this “mixed gradient problem”, i.e., the variational method and loopy belief propagation. We propose a 3D video integration algorithm, which uses the variational method to find the potential function whose gradient field is closest to the mixed gradient field in the sense of least squares. The video is reconstructed by solving a 3D Poisson equation. The main contributions of our framework lie in three aspects: first, we derive a straightforward extension of current 2D gradient technique to 3D space, thus resulting in a novel video editing framework, which is very different from all current video editing software; secondly, we propose using a fast and accurate 3D discrete Poisson solver which uses diagonal multigrids to solve the 3D Poisson equation, which is up to twice as fast as a simple conventional multigrid algorithm; finally, we introduce a set of new applications, such as face replacement and painting, high dynamic range video compression and graphcut based video compositing. A set of gradient operators is also provided to the user for editing purposes. We evaluate our algorithm using a variety of examples for image/video or video/video pairs. The resulting video can be seamlessly reconstructed.     

基于遗传策略的图像灰度多阈值选择方法

阈值法是图像处理中阈值选择的最重要方法之一,吸引了很多研究者的注意力。ChunDN等人将遗传算法引入到阈值选择问题中,提出了基于遗传算法的鲁棒图像分割准则。文中对遗传算法做了改进,提出了自己的图像分割方法,并针对多阈值选择中计算量太大的问题,提出了自己的算法。通过实验将该算法与模拟退火算法进行了比较,结果充分显示了算法的有效性。     

一种快速图像块填充算法及其在遥感影像处理中的应用

针对Drori的图像块填充算法计算复杂度高,计算量大的缺点,提出了一个快速的改进算法。并结合光学遥感影像的特点,将其应用到遥感影像中的厚云及阴影去除上。实验结果表明,在能够取得近似相同结果的情况下,本文算法与Drori算法相比,能够较好地缩短计算时间。     

一种基于样本块的快速图像修复算法

分析了Criminisi等人提出的基于样本块的图像修复算法,针对其不足,提出一种改进的基于样本块的快速图像修复方法.引入新的度量函数更新置信度,使优先级的计算更加准确;待匹配块的再筛选策略降低了选择最佳匹配块的随机性;已修复样本块邻域检测避免了全局范围内寻找破损边缘.实验结果表明:该方法取得了较好的修复效果,同时提高了...     

Unsupervised multiphase segmentation: A recursive approach

We propose an unsupervised multiphase segmentation algorithm based on Bresson et al.’s fast global minimization of Chan and Vese’s two-phase piecewise constant segmentation model. The proposed algorithm recursively partitions a region into two subregions, starting from the largest scale. The segmentation process automatically terminates and detects when all the regions cannot be partitioned further. The number of regions is not given and can be arbitrary. Furthermore, this method provides a full hierarchical representation that gives a structure of a given image.     

Fast and scalable selection algorithms with applications to median filtering

The main contributions of this paper are in designing fast and scalable parallel algorithms for selection and median filtering. Based on the radix-/spl omega/ representation of data and the prune-and-search approach, we first design a fast and scalable selection algorithm on the arrays with reconfigurable optical buses (AROB). To the authors' knowledge, this is the most time efficient algorithm yet published, especially compared to the algorithms proposed by Han et al (2002) and Pan (1994). Then, given an N /spl times/ N image and a W /spl times/ W window, based on the proposed selection algorithm, several scalable median filtering algorithms are developed on the AROB model with a various number of processors. In the sense of the product of time and the number of processors used, most of the proposed algorithms are time or cost optimal.     

使用超像素分割与图割的网状遮挡物检测算法

针对由于摄影角度受限,一些自然图像被铁丝网、栅栏、外墙玻璃接缝等网状遮挡物所遮挡的问题,提出了一种用于修复此类图像的网状遮挡物检测算法。对于现有算法使用单像素颜色特征和固定形状特征造成对颜色和形状不均的网状遮挡物检测效果不佳的弊端,首先将图像进行超像素分割,引入颜色与纹理直方图的联合特征来描述超像素块,将基于像素分类问题转换成基于超像素的分类问题,抑制了局部颜色变化造成的误分类;然后,使用图割算法将超像素块进行分类,使网状结构能够沿着光滑的边缘进行延伸,不受固定的形状限制,提高了对异形网状结构的检测准确率,并且不依赖Farid等提出的算法（FARID M S,MAHMOOD A,GRANGETTO M.Image de-fencing framework with hybrid inpainting algorithm.Signal,Image and Video Processing,2016,10（7）：1193-1201）所需的人工输入;其次使用新的联合特征训练支持向量机（SVM）分类器并对所有未被分类的超像素块进行分类,得到准确网状遮挡物掩膜;最后,使用SAIST算法对图像进行修复。实验中,获得的网状遮挡物掩膜比Farid等提出的算法所得到的保留了更多的细节,在修复算法不变的同时显著提升了图像修复效果。在使用相同网状遮挡物掩膜的情况下,使用SAIST算法修复得到的图片在峰值信噪比（PSNR）和结构相似性（SSIM）上分别比Farid等提出算法提高了3.06和0.02。新的掩膜检测算法联合SAIST修复算法的总体修复效果对比Farid等提出算法及Liu等提出的算法（LIU Y Y,BELKINA T,HAYS J H,et al.Image de-fencing.Proceedings of the 2008 IEEE Conference on Computer Vision and Pattern Recognition.Washington,DC：IEEE Computer Society,2008：1-8）有了明显提升。实验结果表明,所提算法提升了网状遮挡物的检测准确性,得到了效果更好的去除网状遮挡物的图像。     

葫芦烙画的计算机系统仿真

为了获得葫芦烙画图像的计算机仿真效果,对Efros等人提出的以区块为基础的纹理传输算法进行改进,并对传输结果图像进行了有效的融合处理。该方法首先在YCbCr颜色空间中进行图像间亮度相似性匹配,通过纹理传输获得烙画图像,对传输结果图像根据Levin的最小二乘法原理,设计了一种基于动态权重控制的16点约束图像变形算法,实现了烙画图像的变形控制,然后在lαβ空间中实现了图像融合。最后将融合结果图像与泊松图像编辑方法的融合效果进行了对比分析。实验结果表明,该算法所获得的仿真结果图像接近真实葫芦烙画图像效果。     

稀疏形状先验的脑肿瘤图像分割

目的 在脑部肿瘤图像的分析过程中,准确分割出肿瘤区域对于计算机辅助脑部肿瘤疾病的诊断及治疗过程具有重要意义。然而,由于脑部图像常存在结构复杂、边界模糊、灰度不均以及肿瘤内部存在明暗区域的问题,使得肿瘤图像分割工作面临严峻挑战。为了克服上述困难,更好地实现脑部肿瘤图像分割,提出一种基于稀疏形状先验的脑肿瘤图像分割算法。方法 首先,研究脑部肿瘤图像的配准与形状描述,并以此为基础构建脑部肿瘤的稀疏形状先验约束模型;继而,将该稀疏形状先验约束模型与区域能量描述方法相结合,构建基于稀疏形状先验的能量函数;最后,对能量函数进行优化及迭代,输出脑部肿瘤区域分割结果。结果 本文使用脑胶质瘤公开数据集BraTS2017进行算法测试,本文算法的分割结果与真实数据之间的平均相似度达到93.97%,灵敏度达到91.3%,阳性预测率达到95.9%。本文算法的实验准确度较高,误判率较低,鲁棒性较强。结论 本文算法能够结合水平集方法在拓扑结构描述和稀疏表达方法在复杂形状表达方面的优势,同时由于加入了形状约束,能够有效削弱肿瘤内部明暗区域对分割结果造成的影响,从而更准确和稳定地实现脑部肿瘤图像分割。