Palm vein recognition using adaptive Gabor filter

Vein pattern recognition is one of the newest biometric techniques researched today. One of the reliable and robust personal identification authentication approaches using palm vein patterns is presented in this paper. In our work, we consider the palm vein as a piece of texture and apply texture-based feature extraction techniques to palm vein authentication. A Gabor filter provides the optimized resolution in both the spatial and frequency domains, thus it is a basis for extracting local features in the palm vein recognition. However, Gabor filter has many potential parameter combinations to use, and it is a common practice now to use multiple Gabor filters or to determine desired single combination by experience. The overall aim of this work is to discuss the optimization algorithm that determines the best parameter values of a single Gabor filter for palm vein recognition. In order to obtain effective pattern of palm vascular, we proposed an innovative and robust adaptive Gabor filter method to encode the palm vein features in bit string representation. The bit string representation, called VeinCode, offers speedy template matching and enables more effective template storage and retrieval. The similarity of two VeinCodes is measured by normalized Hamming distance. A total of 4140 palm vein images were collected form 207 persons to verify the validity of the proposed palm vein recognition approach. High accuracy has been obtained by the proposed method and the speed of this method is rapid enough for real-time palm vein recognition. Experimental results demonstrate that our proposed approach is feasible and effective in palm vein recognition.     

Local and global Gabor features for object recognition

Invariant object recognition is one of the most central problems in computer vision. To be successful when occlusion and distortions are present, object recognition has to be based on local features. The features should express the significant information while being robust in the presence of noise and distortions, and stable in terms of feature parameters. In this study, Gabor filtering based features is analyzed in terms of the above requirements. Two classes of Gabor features are introduced: global Gabor features and fundamental frequency Gabor features. The Gabor filter response and stability issues are analyzed in terms of the filtering parameters. The robustness of the proposed features is examined through experiments. Both analytical and experimental results indicate that when certain conditions on the filter parameters are met, Gabor filtering can be reliably used in low-level feature extraction in image processing, and the filter responses can be used to construct robust invariant recognition systems.     

Gabor滤波器参数设计及其在虹膜识别中的应用

利用二维Gabor滤波器组编码虹膜纹理的方法,已被广泛地应用于虹膜识别中。该方法的关键是滤波器组的参数设计,直接影响着识别准确率。深入分析了二维Gabor滤波器各参数的作用,提出了一种适用于虹膜纹理特征提取的Gabor滤波器参数设计方法。该方法根据理论分析建立起参数间的关系,借助傅里叶变换和频谱分析确定参数取值。实验证明,依据该方法设计的滤波器组用于虹膜识别,效果好、识别率高。     

基于Gabor滤波器的快速人脸识别算法

针对传统人脸识别方法中所提取特征维数高、计算量大等缺点,提出一种新的正面人脸识别算法。新算法融合了半边人脸识别方法、Gabor滤波器、基于互信息判据的Gabor特征筛选来进行人脸识别。新算法将人脸图像分为左右两个部分,计算并比较人脸图像左右半边脸的熵,选取熵值较大的半边人脸图像进行Gabor特征提取。利用二值分类器判别单个Gabor特征的分类能力,选取分类能力较强的特征（最具判决力的特征）。再利用互信息判据对Gabor特征进行第二次筛选,以减小特征之间的冗余度。最后利用最近邻判别器来进行人脸识别。实验结果表明,新算法的识别率优于传统半边脸识别方法,识别速度也优于传统的利用Gabor滤波器进行特征提取的方法。     

基于YUV模型和Gabor滤波器的快速目标识别方法

为了满足移动机器人准确快速的目标识别要求,给出了一种基于YUV颜色模型和Gabor小波相结合的目标识别方法.该方法首先利用YUV色彩模型快速地对目标进行预识别,然后利用Gabor小波滤波器组对预识别后的结果进行精确识别.机器人对彩色足球的识别实验结果表明,该算法在准确识别目标的前提下,可以达到约12帧每秒的图像处理速度.     

基于Gabor滤波器和BP神经网络的人脸皮肤皱纹区域自动识别

由于色斑和毛孔等强噪声的干扰,人脸皱纹识别特别是对面部细纹理的识别受到了严重影响。针对上述问题提出了一种基于Gabor滤波器和BP神经网络相结合的人脸皱纹识别算法。通过训练好的BP神经网络人脸皮肤图像首先识别是否存在皱纹,再分别自动标注存在皱纹的区域。本算法首先基于不同年龄的多幅人脸照片创建皱纹样本库,采用样本库训练神经BP网络。其次分别选取含皱纹和不含皱纹的图片,然后用Gabor滤波器组计算出图片的频谱特征,将它们作为训练样本,训练得到用于识别的BP神经网络。大量测试结果表明,本算法能够消除或减少色斑、毛孔等噪声的干扰,对有皱纹区域和无皱纹区域的识别率可达到85%以上。     

Analysis of variance of Gabor filter banks parameters for optimal face recognition

Gabor filter banks constitute a very robust tool to extract discriminant information from a visual scene. After the now “classical” bank with 5 frequencies and 8 orientations proposed by Lades et al. and Wiskott et al., many other parametrizations of a Gabor filter bank have appeared. In order to find the optimal parametrization for a face recognition experiment, we have performed a 6-way analysis of variance of Gabor parameters using FERET, FRAV2D, FRAV3D, FRGC and XM2VTS face databases, including frontal and turned poses, facial expressions, occlusions and changes of illumination. Considering independent criteria to find the optimal Gabor filter bank, the bank with the highest recognition rate was found to have 6 frequencies and narrower Gaussian widths in the space domain. These results were obtained with Mahalanobis distance for a k-NN classifier, with analytical and holistic Gabor feature vectors. Moreover about 20% of the banks studied here obtained in average a better performance than the classical bank. For most of the databases considered, the highest recognition rates have been achieved with analytical representations (frontal images, images with turns or occlusions), with a holistic preponderance for images with gestures or changes of illumination. The inferiority found for holistic Gabor representations versus their analytical counterparts can be explained for the intrinsic redundancy and the size of the feature vectors of this kind of representation.     

Improving Gabor noise

We have recently proposed a new procedural noise function, Gabor noise, which offers a combination of properties not found in the existing noise functions. In this paper, we present three significant improvements to Gabor noise: 1) an isotropic kernel for Gabor noise, which speeds up isotropic Gabor noise with a factor of roughly two, 2) an error analysis of Gabor noise, which relates the kernel truncation radius to the relative error of the noise, and 3) spatially varying Gabor noise, which enables spatial variation of all noise parameters. These improvements make Gabor noise an even more attractive alternative for the existing noise functions.     

改进Gabor加权分析方法在人脸识别中的应用

为提高Gabor对人脸结构特征和内容信息的保留能力,解决人脸识别中对表情等抗噪性差的缺点,提出一种基于改进Gabor加权分析的人脸识别算法。该方法通过对归一化的人脸进行多尺度Gabor分析,并依据相同滤波窗口参数进行归类合并,最后对该信号进行加权比对得到识别结果。实验证明,该方法很好地兼顾人脸结构特征和内容信息,具有良好的抗噪性和识别率。     

Polyhedral object recognition by indexing

In computer vision, the indexing problem is the problem of recognizing a few objects in a large database of objects while avoiding the help of the classical image-feature-to-object-feature matching paradigm. In this paper we address the problem of recognizing three-dimensional (3-D) polyhedral objects from 2-D images by indexing. Both the objects to be recognized and the images are represented by weighted graphs. The indexing problem is therefore the problem of determining whether a graph extracted from the image is present or absent in a database of model graphs. We introduce a novel method for performing this graph indexing process which is based both on polynomial characterization of binary and weighted graphs and on hashing. We describe in detail this polynomial characterization and then we show how it can be used in the context of polyhedral object recognition. Next we describe a practical recognition-by-indexing system that includes the organization of the database, the representation of polyhedral objects in terms of 2-D characteristic views, the representation of this views in terms of weighted graphs and the associated image processing. Finally, some experimental results allow the evaluation of the system performance.     

Improving performance on object recognition for real-time on mobile devices

Augmented reality has been on the rise due to the proliferation of mobile devices. At the same time, object recognition has also come to the fore. In particular, many studies have focused on object recognition based on markerless matching. However, most of these studies have focused on desktop systems, which can have high performance in terms of CPU and memory, rather than investigating the use of mobile systems, which have been previously unable to provide high-performance object recognition based on markerless matching. In this paper, we propose a method that uses the OpenCV mobile library to improve real-time object recognition performance on mobile systems. First, we investigate the original object recognition algorithm to identify performance bottlenecks. Second, we optimize the algorithm by analyzing each module and applying appropriate code enhancements. Last, we change the operational structure of the algorithm to improve its performance, changing the execution frequency of the object recognition task from every frame to every four frames for real-time operation. During the three frames in which the original method is not executed, the object is instead recognized using the mobile devices accelerometer. We carry out experiments to reveal how much each aspect of our method improves the overall object recognition performance; overall, experimental performance improves by approximately 800 %, with a corresponding reduction of approximately 1 % in object recognition accuracy. Therefore, the proposed technique can be used to significantly improve the performance of object recognition based on markerless matching on mobile systems for real-time operation.     

基于Gabor小波和模型自适应的鲁棒人脸识别方法*

提出了一种基于Gabor小波人脸特征和模型自适应算法的新鲁棒人脸识别方法。该方法在真实识别前,通过用与真实识别相同的环境条件下所获得的人脸图像数据对原始模型进行更新补偿,实现了模型自适应。该模型自适应更新算法是加性的,其具有较低的时间和空间复杂度。通过模型自适应更新,新方法可以有效地减少模型和识别数据间的失配,从而提高识别率。在AT&T和MITCBCL人脸数据库上的测试结果表明,该方法是有效的。     

通用对象识别技术

遵循通用对象识别系统的一般框架,重点讨论了各种特征区域选取、特征区域描述技术,比较了几种主流的识别模型和模型的训练方法,并介绍了对象识别系统的性能评估方法及其常用数据集,最后分析了未来可能的研究发展方向。     

Generalized Gabor filters for palmprint recognition

Orientation-based coding approaches have recently been widely employed for face and palmprint recognition where generally, one starts with a set of Gabor filters to extract orientation information and then proceeds to code dominant orientations as features for each point of the palmprint. However, as the Gabor filter is developed to model two-dimensional receptive fields of simple cells in straits cortex, it might not be our best choice when dealing with curved and complex structures inherent in the palmprint texture. Motivated by this intuition, this paper shows that Gabor filters are a subset of a bigger family of filters which we refer to as generalized Gabor filter (GGF). Depending on the values of its parameters, a GGF takes a rather diverse shapes and orientations, which results in a potentially finer feature extraction capability. We show this improved capability by employing GGFs in the palmprint verification process. In applying our method, two different sub-banks of GGFs are defined for the orientation-based feature extraction of palmprints, and when compared with Gabor filters, it will be shown that GGFs have the upper hand in capturing orientation features. Furthermore, compared with the competitive code—one of the well-known orientation-based coding methods—the number of employed orientations is reduced to half. This would automatically compensate for a double usage of the filter banks, which otherwise could increase the time complexity of using GGFs. These ideas are further elaborated using a set of experiments on PolyU II and PolyU 2D/3D palmprint databases. The results show the preeminence of using GGFs both in terms of accuracy and efficiency.     

基于Gabor纹理特征的人脸识别方法*

为了降低人脸Gabor特征的维数,提出了一种新的基于Gabor幅值的纹理表征(GMTR)方法用于人脸识别。GMTR由伽玛分布(ΓD)拟合Gabor幅值的分布来刻画,拟合的ΓD参数作为纹理特征。在FERET和Yale人脸库上的实验结果显示GMTR的识别性能优于传统的Gabor幅值特征,表明纹理特征具有更强的鉴别力。     

融合Gabor小波和贝叶斯的人脸识别算法

由于Gabor小波和贝叶斯方法都可以通过不同的机制来减少类内差异,提出了融合Gabor和贝叶斯的人脸识别方法。该方法首先通过人脸图像特征点与Gabor滤波器的卷积来提取特征,借鉴“作差法”形成“类内差”和“类间差”空间,并用2DPCA对差异空间进行降维,最后用贝叶斯方法进行分类。通过在AR和FERET人脸库上的实验表明,与传统的方法相比较,该方法降低了运算量,提高了识别率,对具有表情及光照变化的人脸具有较高的识别率。     

基于Gabor滤波器的指纹图像快速增强

研究并实现了利用Gabor滤波器对指纹图像增强的算法。改进了指纹图像方向图和纹线频率的提取方法,同时也对Gabor滤波器的快速实现方法进行研究,首先把Gabor滤波器分解为多个不同方向上有着不同参数的一维高斯滤波器的组合,然后通过递归的方法分别实现这些高斯滤波器,最后实现了Gabor滤波器的快速算法在指纹图像增强中的应用。实践表明,该方法效果良好,速度快,能大幅度提高指纹图像质量。     

Efficient Gabor filter design for texture segmentation

Gabor filters have been successfully applied to a broad range of image processing tasks. The present paper considers the design of a single filter to segment a two-texture image. A new efficient algorithm for Gabor-filter design is presented, along with methods for estimating filter output statistics. The algorithm draws upon previous results that showed that the output of a Gabor-filtered texture is modeled well by a Rician distribution. A measure of the total output power is used to select the center frequency of the filter and is used to estimate the Rician statistics of the Gabor-filtered image. The method is further generalized to include the statistics of postfiltered outputs that are generated by a Gaussian filtering operation following the Gabor filter. The new method typically requires an order of magnitude less computation to design a filter than a previously proposed method. Experimental results demonstrate the efficacy of the method.     

Gabor变换仿生人脸识别

针对主成分分析(PCA) 方法在特征提取和降维方面的不足,提出一种Gabor特征筛选的仿生人脸识别方法.首先提取人脸图像Gabor特征向量, 经2DPCA方法降维处理后用仿生识别方法对其进行人脸识别.在AR 人脸库上验证了该方法的有效性.实验结果显示, 该方法的分类准确性高于仿生识别方法和PCA 等方法.     

Fast occluded object tracking by a robust appearance filter

We propose a new method for object tracking in image sequences using template matching. To update the template, appearance features are smoothed temporally by robust Kalman filters, one to each pixel. The resistance of the resulting template to partial occlusions enables the accurate detection and handling of more severe occlusions. Abrupt changes of lighting conditions can also be handled, especially when photometric invariant color features are used, The method has only a few parameters and is computationally fast enough to track objects in real time.