The pose problem is one of the bottlenecks in automatic face recognition. We argue that one of the diffculties in this problem is the severe misalignment in face images or feature vectors with different poses. In this paper, we propose that this problem can be statistically solved or at least mitigated by maximizing the intra-subject across-pose correlations via canonical correlation analysis (CCA). In our method, based on the data set with coupled face images of the same identities and across two different poses, CCA learns simultaneously two linear transforms, each for one pose. In the transformed subspace, the intra-subject correlations between the different poses are maximized, which implies pose-invariance or pose-robustness is achieved. The experimental results show that our approach could considerably improve the recognition performance. And if further enhanced with holistic+local feature representation, the performance could be comparable to the state-of-the-art.
The geometrical alignment can directly reduce the pose difference, but the alignment itself cannot deal with the occlusion. Statistical approaches can mitigate the occlusion problem to some extent, their performance highly relies on the training data. Thus, combining geometrical and statistical information is an alternative way to tackle the pose problem. We term this kind of methods the hybrid approach. One way to integrate geometrical and statistical information is combining local statistical models with coarse geometrical alignment. Kanade and Yamada @cite_22 proposed a probabilistic framework to build and combined local statistical models for recognizing faces under different viewpoints, in which the statistical models are built on local patches on face images. Based on this framework, Liu and Chen @cite_26 used a simple 3D ellipsoid model to align patches across different pose, while @cite_29 aligned the patches by learning 2D affine transform for each patch pair via a Lucas-Kanade @cite_2 like optimization procedure. Unlike the above methods that concern on matching local patches, Lucey and Chen @cite_7 extended Kanade and Yamada's work by building similar statistical models between holistic non-frontal faces and local patches on frontal face.
@cite_26 @cite_22 @cite_7 @cite_29 @cite_2
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Researchers have been working on human face recognition for decades. Face recognition is hard due to different types of variations in face images, such as pose, illumination and expression, among which pose variation is the hardest one to deal with. To improve face recognition under pose variation, this paper presents a geometry assisted probabilistic approach. We approximate a human head with a 3D ellipsoid model, so that any face image is a 2D projection of such a 3D ellipsoid at a certain pose. In this approach, both training and test images are back projected to the surface of the 3D ellipsoid, according to their estimated poses, to form the texture maps. Thus the recognition can be conducted by comparing the texture maps instead of the original images, as done in traditional face recognition. In addition, we represent the texture map as an array of local patches, which enables us to train a probabilistic model for comparing corresponding patches. By conducting experiments on the CMU PIE database, we show that the proposed algorithm provides better performance than the existing algorithms. Current automatic facial recognition systems are not robust against changes in illumination, pose, facial expression and occlusion. In this paper, we propose an algorithm based on a probabilistic approach for face recognition to address the problem of pose change by a probabilistic approach that takes into account the pose difference between probe and gallery images. By using a large facial image database called CMU PIE database, which contains images of the same set of people taken from many different angles, we have developed a probabilistic model of how facial features change as the pose changes. This model enables us to make our face recognition system more robust to the change of poses in the probe image. The experimental results show that this approach achieves a better recognition rate than conventional face recognition methods over a much larger range of pose. For example, when the gallery contains only images of a frontal face and the probe image varies its pose orientation, the recognition rate remains within a less than 10 difference until the probe pose begins to differ more than 45 degrees, whereas the recognition rate of a PCA-based method begins to drop at a difference as small as 10 degrees, and a representative commercial system at 30 degrees. Most pose robust face verification algorithms, which employ 2D appearance, rely heavily on statistics gathered from offline databases containing ample facial appearance variation across many views. Due to the high dimensionality of the face images being employed, the validity of the assumptions employed in obtaining these statistics are essential for good performance. In this paper we assess three common approaches in 2D appearance pose mismatched face recognition literature. In our experiments we demonstrate where these approaches work and fail. As a result of this analysis, we additionally propose a new algorithm that attempts to learn the statistical dependency between gallery patches (i.e. local regions of pixels) and the whole appearance of the probe image. We demonstrate improved performance over a number of leading 2D appearance face recognition algorithms. Variation due to viewpoint is one of the key challenges that stand in the way of a complete solution to the face recognition problem. It is easy to note that local regions of the face change differently in appearance as the viewpoint varies. Recently, patch-based approaches, such as those of Kanade and Yamada, have taken advantage of this effect resulting in improved viewpoint invariant face recognition. In this paper we propose a data-driven extension to their approach, in which we not only model how a face patch varies in appearance, but also how it deforms spatially as the viewpoint varies. We propose a novel alignment strategy which we refer to as ldquostack flowrdquo that discovers viewpoint induced spatial deformities undergone by a face at the patch level. One can then view the spatial deformation of a patch as the correspondence of that patch between two viewpoints. We present improved identification and verification results to demonstrate the utility of our technique. Image registration finds a variety of applications in computer vision. Unfortunately, traditional image registration techniques tend to be costly. We present a new image registration technique that makes use of the spatial intensity gradient of the images to find a good match using a type of Newton-Raphson iteration. Our technique is taster because it examines far fewer potential matches between the images than existing techniques Furthermore, this registration technique can be generalized to handle rotation, scaling and shearing. We show how our technique can be adapted tor use in a stereo vision system.