Enhancing face matching in a suitable binary environment

In recent days, there has been increasing need for recognition of unconstrained face images, such as those collected from the web or captured by mobile devices and video surveillance cameras. In such real world scenarios, human faces could be easily occluded by other objects that make the face recognition task as a complex one. Satisfactory performance has been achieved earlier but often only in the controlled environments. But it is very tedious to obtain holistic face images for unconstrained face recognition. Thus, in order to avoid the degradation of face images and the huge variations due to illumination, pose, occlusion and expression, a new Robust Face Recognition approach is proposed. In this approach, the partial face recognition using Scale Invariant Feature Transform (SIFT) technique is combined with Multi-directional Multi-level Dual Cross Patterns (DCP) technique that makes the recognition task as a robust one when compared to other face recognition approaches. Then, the Robust Point Set Matching (RPSM) is used to match the corresponding stable keypoints from both the gallery image and probe face image. Finally, PNN and K-NN classification are used to classify the face images even with the presence of occlusion, random partial crop, illumination, pose and exaggerated facial expression. The proposed robust face recognition system is evaluated based on the performance parameters such as sensitivity, specificity, accuracy, precision and recall.

Face recognition includes analysis of an image and extracting its facial features which will help to discriminate it from others. Scale invariant feature transform (SIFT) to extract distinctive invariant features from images can be used to perform reliable matching. The features extracted are invariant to rotation, image scale and illumination. Systematic investigation of face recognition using SIFT features has been done. Being high distinctive features, every feature can be matched correctly with high probability against a huge database of features from many images. Result shows that SIFT is flexible recognition algorithm as compared to Contour matching algorithm for heterogeneous images. Both the algorithms are experimentally evaluated on AT&T, YALE and IIT-KANPUR databases with moderate subject size. Though Contour matching provides computational simplicity, SIFT provides efficient face recognition technique under pose, expression and varying illumination condition. Experimentally it confirms that Contour matching outperforms when the database is small but for large databases Scale Invariant Feature Transform (SIFT) gives more than 90% recognition rate.

The main goal of this work is to develop a fully automatic face recognition algorithm. Scale Invariant Feature Transform (SIFT) has sparingly been used in face recognition. In this paper, a Modified SIFT (MSIFT) approach has been proposed to enhance the recognition performance of SIFT. In this paper, the work is done in three steps. First, the smoothing of the image has been done using DWT. Second, the computational complexity of SIFT in descriptor calculation is reduced by subtracting average from each descriptor instead of normalization. Third, the algorithm is made automatic by using Coefficient of Correlation (CoC) instead of using the distance ratio (which requires user interaction). The main achievement of this method is reduced database size, as it requires only neutral images to store instead of all the expressions of the same face image. The experiments are performed on the Japanese Female Facial Expression (JAFFE) database, which indicates that the proposed approach achieves better performance than SIFT based methods. In addition, it shows robustness against various facial expressions.

In this paper, a novel face representation in terms of dense local image descriptors is proposed. Scale Invariant Feature Transform (SIFT) and Gabor, two of the most popular local image descriptors, at dense grid pixels of a face image are used to represent the face. The efficiency of the representation has been investigated in gender recognition. There are four problems when applying the SIFT to facial gender recognition. (1) There may be only a few keypoints that can be found in a face image due to the missing texture and ill-illumined faces; (2) The SIFT descriptors at the keypoints (we called it sparse SIFT) are distinctive whereas alternative descriptors at non-keypoints (e.g. grid) could cause negative impact on the accuracy; (3) Most of the existing methods employ SIFT descriptors matching in which relative larger image size is required in order that enough keypoints can be found to support the matching and (4) The matching is assumed that the faces are well registered. We provide solutions to the above difficulties in this paper and the problem of recognizing gender using the combination of SIFT descriptors and Gabor of face images is studied. The Gabor representations of the face images are fused with the dense SIFT at the feature-level to improve the accuracy. AdaBoost is adopted to select features and form a strong classifier. The experimental results on a large set of faces have shown that the proposed method can achieve high accuracies even for faces that are not aligned.

In recent years, Ambient Intelligence (AmI) has attracted increased attention within the advanced technology industry in an effort to modernize and develop a more intelligent and reliable information system. Technologies to detect a specific object in images are expected to further expand to wide range of applications, such as car detection functions for Intelligent Transport System (ITS) and other systems. Computer vision and pattern recognition are emerging fast and will continue to grow together with local feature detection methods. In this paper, we propose an object detection and tracking system which is based on Scale Invariant Feature Transform (SIFT) and Speed Up Robust Features (SURF) feature extraction methods. From the evaluation results, we observe that the accuracy of matched keypoints of SURF algorithm are higher than SIFT.

Scale Invariant Feature Transform (SIFT) is used for local features description of images. The proposed technique employs SIFT in order to match binary images. While the employment of SIFT descriptors on binary image databases could be possible, its power is rather limited. The novelty of the proposed algorithm is make use of SIFT for binary image matching by taking the power of Hough Transform (HT) in line detection. HT can be used on any line orientation. Thus, HT investigates lines as criteria for binary image similarity beside SIFT features for local and corner descriptions. The evaluation is achieved and experimental highlights the superiority of this approach for binary images which contains straight lines.

얼굴추적은 3차원 공간상에서 머리(head)와 안면(face)의 움직임을 추정하는 기술로, 얼굴 표정 감정인식과 같은 상위 분석단계의 중요한 기반기술이다. 본 논문에서는 AAM 기반의 얼굴추적 알고리즘을 제안한다. AAM은 변형되는 대상을 분할하고 추적하는데 광범위하게 적용되고 있다. 그러나 여전히 여러 가지 해결해야할 제약사항들이 있다. 특히 자체중첩(self-occlusion)과 부분적인 중첩, 그리고 일시적으로 완전히 가려지는 완전중첩 상황에서 보통 국부해에 수렴(local convergence)하거나 발산하기 쉽다. 본 논문에서는 이러한 중첩상황에 대한 AAM의 강인성을 향상시키기 위해서 SIFT 특징을 이용하고 있다. SIFT는 일부 영상의 특징점으로 안정적인 추적이 가능하기 때문에 자체와 부분중첩에 효과적이며, 완전중첩의 상황에도 SIFT의 전역적인 매칭성능으로 별도의 재초기화 없이 연속적인 추적이 가능하다. 또한 추적과정에서 큰 자세변화에 따른 움직임을 효과적으로 추정하기 위해서 다시점(multi-view) 얼굴영상의 SIFT 특징을 온라인으로 등록하여 활용하고 있다. 제안한 알고리즘의 이러한 강인성은 위 세 가지 중첩상황에 대해서 기존 알고리즘들과의 비교실험을 통해서 보여준다. Face tracking is to estimate the motion of a non-rigid face together with a rigid head in 3D, and plays important roles in higher levels such as face/facial expression/emotion recognition. In this paper, we propose an AAM-based face tracking algorithm. AAM has been widely used to segment and track deformable objects, but there are still many difficulties. Particularly, it often tends to diverge or converge into local minima when a target object is self-occluded, partially or completely occluded. To address this problem, we utilize the scale invariant feature transform (SIFT). SIFT is an effective method for self and partial occlusion because it is able to find correspondence between feature points under partial loss. And it enables an AAM to continue to track without re-initialization in complete occlusions thanks to the good performance of global matching. We also register and use the SIFT features extracted from multi-view face images during tracking to effectively track a face across large pose changes. Our proposed algorithm is validated by comparing other algorithms under the above 3 kinds of occlusions.

In this paper, an affine invariance feature detection method based on Scale Invariant Feature Transform (SIFT) and Maximally Stable Extremal Regions (MSER) is proposed. Classical SIFT algorithm is not robust to affine deformations, because it is based on DOG detector which extracts circle regions for keypoint location. In order to overcome this disadvantage, DOG detector in conventional SIFT algorithm is replaced by MSER detector which is robust to affine deformation. Then these regions are normalized and extracted using SIFT. Simulation studies are carried out to show the effectiveness of the proposed method to affine transform in comparison to traditional SIFT algorithm.

In allusion to non-rigid registration of medical images, the paper gives a novel algorithm based on improved Scale Invariant Features Transform (SIFT) feature matching algorithm. First, Harris corner detection algorithm is used in the process of scale invariant feature extraction, so the number of right matching points is increased; with regard to the feature points detected in the scale space, an improved SIFT feature extraction algorithm with global context vector is presented to solve the problem that SIFT descriptors result in a lot of mismatches when an image has many similar regions. On this basis, affine transformation is chosen to implement the non-rigid registration, and weighted mutual information (WMI) measure and Particle Swarm Optimization (PSO) algorithm are also chosen to optimize the registration process. The experimental results show that the method can achieve better registration results than the method based on mutual information.

The current national standards of face recognition do not put the placement of light for a clear description, only said that the light should be uniform when face recognition, no overexposure and underexposure. In this paper, we present a novel database and use different face recognition algorithms to determine the placement of light during face recognition. For this study, we have chosen ten widely-used face recognition algorithms: principal component analysis(PCA), linear discriminant analysis(LDA), independent component analysis(ICA), nonnegative matrix factorization (NMF), histogram of oriented gradient(HOG), scale-invariant feature transform(SIFT), face recognition, CosFace, ArcFace, and Combined Margin. We use a novel database that contains face images with a wide range of illumination angles to analyze the relationship between these algorithms and illumination angles. The results of this experiment indicate that the horizontal illumination angle of the light should be controlled in the range from -10° to 10° and the vertical illumination angle should be controlled in the range from -10° to 10°.

Efficient detection and reliable matching of image features constitute a fundamental task in computer vision. When real-time operation is required, the solution to this problem becomes a real challenge, because of increased processing requirements. Scale Invariant Feature Transform (SIFT) is considered as a stable and robust algorithm for the extraction of invariant features, however special hardware is required for high frame-rate applications, in order to overcome its computational complexity in real-time. In this paper, a complete processor for SIFT feature matching in video sequences is presented. It performs SIFT feature extraction and matching, as well as rejection of false correspondences using the random sample consensus (RANSAC) algorithm. The processor was evaluated using metrics like response, repeatability and recall. It was found that the proposed fixed-point hardware implementation has a comparable performance with software implementations of SIFT. The processor architecture can process more than 36 fps with resolution 640×480, when it is implemented in Cyclone IV FPGA technology.

Scale invariant feature transform(SIFT) is an algorithm to extract distinctive and invariant features from images to achieve reliable object matching between different images in variant scales and rotations. However, SIFT's huge computation impedes its real-time implementation. In this paper, a Fast-Gaussian SIFT(FG-SIFT) is proposed. Keypoint detection is optimized in FG-SIFT. SIFT's 2-D difference of Gaussian(DoG) in Gaussian Scale-Space(GSS) is separated into two 1-D DoG in x and y dimensions, and the level of scales in DoG pyramid is also reduced. The experiment shows that FG-SIFT reduces the computational complexity about 95% in GSS construction, also increases the accuracy of keypoint detection. Subsequently, the accuracy of generated features is increased 162%, and the accuracy of matched features is increased 8%. Apart from optimization in algorithm level, a hardware architecture of FG-SIFT's keypoint detection module is proposed. With a parallel architectural incorporating a five-stage pipeline, the execution time of keypoint detection is only 1.42ms@Xilinx Virtex5. Compared to conventional works, the speed is 21% faster than the fastest solution [9](ASIC), and hardware resources are 70% less than the most resources saved solutions [5] [6](Xilinx Virtex5).

Face recognition methods, which usually represent face images using holistic or local facial features, rely heavily on alignment. Their performances also suffer a severe degradation under variations in expressions or poses, especially when there is one gallery per subject only. With the easy access to high-resolution (HR) face images nowadays, some HR face databases have recently been developed. However, few studies have tackled the use of HR information for face recognition or verification. In this paper, we propose a pose-invariant face-verification method, which is robust to alignment errors, using the HR information based on pore-scale facial features. A new keypoint descriptor, namely, pore-Principal Component Analysis (PCA)-Scale Invariant Feature Transform (PPCASIFT)-adapted from PCA-SIFT-is devised for the extraction of a compact set of distinctive pore-scale facial features. Having matched the pore-scale features of two-face regions, an effective robust-fitting scheme is proposed for the face-verification task. Experiments show that, with one frontal-view gallery only per subject, our proposed method outperforms a number of standard verification methods, and can achieve excellent accuracy even the faces are under large variations in expression and pose.

There remain many difficult problems in computer vision research such as object recognition, three dimensional reconstruction, object tracking, etc. And the basis of solving these problems relies on image matching. The scale invariant feature transform (SIFT) algorithm has been widely used for image matching application. The SIFT algorithm can successfully extract the most descriptive feature points in given input images taken under different viewpoints. However, the performance of the original SIFT algorithm degrades under the influence of noise. We propose to modify the SIFT algorithm to produce better invariant feature points for image matching under noise. We also propose to employ the Earth mover's distance (EMD) as the measurement of similarity between two descriptors. We present extensive experiment results to demonstrate the performance of the proposed methods in image matching under noise.

To alleviate the limitations that existing face recognition methods, this paper describes a new face recognition method based on scale invariant feature transform (SIFT) and fuzzy reasoning. Experimental results demonstrate that the proposed method yields a better performance in terms of the correct classification percentages compared with the recent face recognition algorithms.