基于多分辨率塔式结构的幻觉脸技术的研究

提出的基于多分辨率塔式结构的幻觉脸算法,使用改进的图像金字塔建立标准人脸训练库作为学习模型,能在多尺度、多分辨率上训练出更有效的先验知识.然后在匹配复原过程中引入一种新思路,先结合塔状父结构搜索出拉普拉斯金字塔中最匹配的4个高频细节,再将这4个高频细节进行加权平均后的结果作为丢失的人脸图像的高频细节,最终复原出超分辨率人脸图像.实验结果表明,该算法对64×64大小的低分辨率人脸图像增强16倍,复原出的256×256大小的超分辨率人脸图像更加平滑,减小了一定的噪声干扰.     

Robust face detection and analysis

This paper presents a method which utilizes color, local symmetry and geometry information of human face based on various models. The algorithm first detects most likely face regions or ROIs (Region-Of-Interest) from the image using face color model and face outline model, produces a face color similarity map. Then it performs local symmetry detection within these ROIs to obtain a local symmetry similarity map. The two maps and local similarity map are fused to obtain potential facial feature points. Finally similarity matching is performed to identify faces between the fusion map and face geometry model under affine transformation. The output results are the detected faces with confidence values. The experimental results demonstrate its validity and robustness to identify faces under certain variations.     

Cross-view information interaction and feedback network for face hallucination

Hallucinating a photo-realistic frontal face image from a low-resolution (LR) non-frontal face image is beneficial for a series of face-related applications. However, previous efforts either focus on super-resolving high-resolution (HR) face images from nearly frontal LR counterparts or frontalizing non-frontal HR faces. It is necessary to address all these challenges jointly for real-world face images in unconstrained environment. In this paper, we develop a novel Cross-view Information Interaction and Feedback Network (CVIFNet), which simultaneously handles the non-frontal LR face image super-resolution (SR) and frontalization in a unified framework and interacts them with each other to further improve their performance. Specifically, the CVIFNet is composed of two feedback sub-networks for frontal and profile face images. Considering the reliable correspondence between frontal and non-frontal face images can be crucial and contribute to face hallucination in a different manner, we design a cross-view information interaction module (CVIM) to aggregate HR representations of different views produced by the SR and frontalization processes to generate finer face hallucination results. Besides, since 3D rendered facial priors contain rich hierarchical features, such as low-level (e.g., sharp edge and illumination) and perception level (e.g., identity) information, we design an identity-preserving consistency loss based on 3D rendered facial priors, which can ensure that the high-frequency details of frontal face hallucination result are consistent with the profile. Extensive experiments demonstrate the effectiveness and advancement of CVIFNet.     

基于2D-PCA特征描述的非负权重邻域嵌入人脸超分辨率重建算法

在基于邻域嵌入人脸图像的超分辨率重建算法中,训练和重建均在特征空间进行,因此,特征选择对算法性能具有较大影响。另外,算法模型对重建权重未加限定,导致负数权重出现而产生过拟合效应,使得重建人脸图像质量衰退。考虑到人脸图像的特征选择以及权重符号限定的重要作用,该文提出一种基于2维主成分分析(2D- PCA)特征描述的非负权重邻域嵌入人脸超分辨率重建算法。首先将人脸图像分成若干子块,利用K均值聚类获得图像子块的局部视觉基元,并利用得到的局部视觉基元对图像子块分类。然后,利用2D-PCA对每一类人脸图像子块提取特征,并建立高、低分辨率样本库。最后,在重建过程中使用新的非负权重求解方法求取权重。仿真实验结果表明,相比其他基于邻域嵌入人脸超分辨率重建方法,所提算法可有效提高权重的稳定性,减少过拟合效应,其重建人脸图像具有较好的主客观质量。     

High-dimensional feature extraction using bit-plane decomposition of local binary patterns for robust face recognition

Transforming an original image into a high-dimensional (HD) feature has been proven to be effective in classifying images. This paper presents a novel feature extraction method utilizing the HD feature space to improve the discriminative ability for face recognition. We observed that the local binary pattern can be decomposed into bit-planes, each of which has scale-specific directional information of the face image. Each bit-plane not only has the inherent local-structure of the face image but also has an illumination-robust characteristic. By concatenating all the decomposed bit-planes, we generate an HD feature vector with an improved discriminative ability. To reduce the computational complexity while preserving the incorporated local structural information, a supervised dimension reduction method, the orthogonal linear discriminant analysis, is applied to the HD feature vector. Extensive experimental results show that existing classifiers with the proposed feature outperform those with other conventional features under various illumination, pose, and expression variations.     

基于相对生成对抗网络的低清小脸幻构

针对当前代表性低清小脸幻构方法存在的视觉真实感弱、网络结构复杂等问题,提出了一种基于相对生成对抗网络的低清小脸幻构方法(tfh-RGAN)。该文方法的网络架构包括幻构生成器和判别器两个部分,通过像素损失函数和相对生成对抗损失函数的联合最小化,实现生成器和判别器的交替迭代训练。其中,幻构生成器结合了残差块、稠密块以及深度可分离卷积算子,保证幻构效果和网络深度的同时降低生成器的参数量;判别器采用图像分类问题中的全卷积网络,通过先后去除批归一化层、添加全连接层,充分挖掘相对生成对抗网络在低清小脸幻构问题上的能力极限。实验结果表明,在不额外显式引入任何人脸结构先验的条件下,该文方法能够以更简练的网络架构输出清晰度更高、真实感更强的幻构人脸。从定量角度看,该文方法的峰值信噪比相较之前的若干代表性方法可提高0.25～1.51 dB。     

自适应局部综合特征加权的单样本人脸特征提取

为了有效地提取单训练人脸样本的特征,提出了一种新的人脸局部特征描述方法,改进了局部二进制模式的方向性描述单一的问题,并且加入了像素间变化趋势幅度的描述,称之为局部综合模式(Local Comprehensive Patterns,LCP).首先对人脸样本图像进行分块,然后每个的分块子图像进行改进LCP算子运算;其次考虑到每个子块的特征对整幅人脸图像的贡献度不一致,提出了贡献度图谱(Contribution Map,CM);最后根据贡献度图谱对每个子块的改进LCP描述进行自适应加权融合形成最终的人脸描述特征,最后在ORL和Yale B库上进行了有效性的测试,与现有的多种算法进行比对,所提出的算法对于非限定环境下人脸的识别有良好的效果.     

An LBP-based multi-scale illumination preprocessing method for face recognition

It is one of the major challenges for face recognition to minimize the disadvantage of il- lumination variations of face images in different scenarios. Local Binary Pattern (LBP) has been proved to be successful for face recognition. However, it is still very rare to take LBP as an illumination preprocessing approach. In this paper, we propose a new LBP-based multi-scale illumination pre- processing method. This method mainly includes three aspects: threshold adjustment, multi-scale addition and symmetry re...     

Single depth map super-resolution via joint non-local self-similarity modeling and local multi-directional gradient-guided regularization

The development of consumer depth cameras makes it possible to acquire depth information of a scene in real-time. However, low resolution and low quality of a depth map has greatly constrained its applications. In this paper, we propose a novel framework for single depth map super-resolution, which considers local and non-local information jointly in the depth map. For the non-local constraint, group-based sparse representation is used to explore non-local self-similarity in the depth map. For the local constraint, a multi-directional gradient-guided regularization is proposed to describe the gradient of the depth map with spatially varying orientations. The former constraint contains the visual artifacts effectively, while the latter restores sharp edge and fine structure. Finally, the two complementary regularizers are jointly casted into a unified optimization framework, where a split Bregman-based technique is developed to tackle the optimization problem. Both quantitative and qualitative evaluations indicate that the proposed method can obtain better reconstruction performance compared with state-of-the-art methods.     

Multiscale residual gradient attention for face anti-spoofing

In the field of face anti-spoofing (FAS), how to extract the representative features to distinguish between real and spoof faces and train the corresponding deep networks are two vital issues. In this paper, we propose a simple but effective end-to-end FAS model based on an innovative texture extractor and a depth auxiliary supervision mechanism. In the feature extraction stage, we first design the residual gradient convolutions based on the redesigned gradient operators, which are used to extract fine-grained texture features. The extraction of texture features is based on multiple scales by dividing the texture differences between living and spoofing faces into three levels reasonably. Then we construct a multiscale residual gradient attention (MRGA) to obtain representative texture features from multiple levels texture features. By combining the proposed feature extractor MRGA and existing vision transformer (ViT), the MRGA-ViT is proposed to generate related semantics and obtain final classification results. In the training stage, we also propose a local depth auxiliary supervision based on a novel adjacent depth loss, which utilizes the correlation information of adjacent pixels adequately compared with traditional depth loss. The proposed MRGA-ViT model achieves competitive performance in generalization and stability ability, e.g., the ACER(%) values of intra testing on OULU-NPU database are 1.8, 2.6, 1.6 ± 1.2 and 1.9 ± 2.7 respectively, the AUC(%) of cross type testing attains 99.45 ± 0.57, the ACER(%) values of cross dataset testing are 28.1 and 36.7 respectively. Experimental results prove that the proposed model is competitive to other state-of-the-art works on generalization and stability performance.     

Multimodal face aging framework via learning disentangled representation

Existing face aging (FA) approaches usually concentrate on a universal aging pattern, and produce restricted aging faces from one-to-one mapping. However, the diversity of living environments impact individuals differently in their oldness. To simulate various aging effects, we propose a multimodal FA framework based on face disentanglement technique of age-specific and age-irrelevant information. A Variational Autoencoder (VAE)-based encoder is designed to represent the distribution of the age-specific attributes. To capture the age-irrelevant features, a cycle-consistency loss of unpaired faces is utilized among various age spans. The extensive experimental results demonstrate that the sampled age-specific codes along with an age-irrelevant feature make the multimodal FA diverse and realistic.     

Learned local Gabor patterns for face representation and recognition

In this paper, we propose Learned Local Gabor Patterns (LLGP) for face representation and recognition. The proposed method is based on Gabor feature and the concept of texton, and defines the feature cliques which appear frequently in Gabor features as the basic patterns. Different from Local Binary Patterns (LBP) whose patterns are predefined, the local patterns in our approach are learned from the patch set, which is constructed by sampling patches from Gabor filtered face images. Thus, the patterns in our approach are face-specific and desirable for face perception tasks. Based on these learned patterns, each facial image is converted into multiple pattern maps and the block-based histograms of these patterns are concatenated together to form the representation of the face image. In addition, we propose an effective weighting strategy to enhance the performances, which makes use of the discriminative powers of different facial parts as well as different patterns. The proposed approach is evaluated on two face databases: FERET and CAS-PEAL-R1. Extensive experimental results and comparisons with existing methods show the effectiveness of the LLGP representation method and the weighting strategy. Especially, heterogeneous testing results show that the LLGP codebook has very impressive generalizability for unseen data.     

Image deblurring via enhanced local maximum intensity prior

The enhanced local maximum intensity prior is proposed in this paper. We find that the intermediate latent image restoration can be enhanced by joining the local maximum intensity with the local maximum gradient, and the quality of the recovered kernel is hereby improved. Our method is based on the fact that the maximum value of local patch pixels and gradients will decrease with the blurring process, which has been proved mathematically and experimentally. This joint prior has been named enhanced local maximum intensity prior. Based on this prior, a new energy function is established and the image deblurring is successfully carried out by alternating optimization strategy. Extensive experiments have been conducted, which shows that our method is more effective compared with the state-of-the-art methods.     

采用自适应加权扩展LBP的单样本人脸识别

提出了一种采用自适应加权扩展LBP(AWELBP,adaptively weighted extended local binarypattern)的单样本人脸描述方法,首先对单样本的人脸图像进行多尺度分块,对子块的图像进行扩展均匀LBP算子运算,同时同步生成图像局部熵图谱(LEM,local entropy map),计算每一子块对整体人脸图像纹理描述的贡献度图谱,根据贡献度图谱对每个子块的LBP直方图进行自适应加权,最后将各子块的LBP直方图进行连接形成人脸特征。本算法在ORL、Yale、Yale B人脸库上对部分遮挡、表情变化、光照变化等环境进行测试,并与传统算法以及与多种LBP改进算法进行比较,结果表明该算法对部分遮挡、表情变化和光照等环境下单样本人脸描述具有较好的效果。     

分块双向2 DPCA融合局部特征的人脸识别

针对(2D)2PCA无法保存某些重要局部特征的问题,提出了一种分块双向二维主成分分析融合局部特征方法。首先,将图像分解为互不重叠的子块,每个子块包含重要的局部信息,利用(2D)2PCA对子块进行特征提取并投影到特征子空间;然后,对每个子块分别设计一个分类器并在一定置信度范围内判别测试样本所属类别。最后,根据所有子块所属类别的置信度之和完成人脸分类。在四个人脸识别数据库上的实验结果表明,相比其它几种人脸识别算法,所提方法取得了更高的识别精度。     

Local maximal margin discriminant embedding for face recognition

In this paper, a manifold learning based method named local maximal margin discriminant embedding (LMMDE) is developed for feature extraction. The proposed algorithm LMMDE and other manifold learning based approaches have a point in common that the locality is preserved. Moreover, LMMDE takes consideration of intra-class compactness and inter-class separability of samples lying in each manifold. More concretely, for each data point, it pulls its neighboring data points with the same class label towards it as near as possible, while simultaneously pushing its neighboring data points with different class labels away from it as far as possible under the constraint of locality preserving. Compared to most of the up-to-date manifold learning based methods, this trick makes contribution to pattern classification from two aspects. On the one hand, the local structure in each manifold is still kept in the embedding space; one the other hand, the discriminant information in each manifold can be explored. Experimental results on the ORL, Yale and FERET face databases show the effectiveness of the proposed method.     

基于局部模式的加权估计纹理分析在人脸识别中的应用

传统的纹理分析方法仅以每个脸部区域的相对贡献来标记全局相似度,针对这种以局部表示全局而导致不能很好地进行特征提取的问题,提出了基于局部模式的加权估计纹理分析(Weighting Estimation for Texture Analysis, WETA)方法。首先使用局部二值模式（Local Binary Pattern, LBP）或者局部相位量化（Local Phase Quantization, LPQ）对图像进行纹理编码,并将其划分成各个大小相等且不重叠的局部小块;然后从相似空间中提取出最具识别力的坐标轴,利用编码与数据库的不同组合估算出权值;最后,通过权值优化给出了最佳解决方案,并采用相似性度量距离转换完成人脸的识别。在FERET和ORL两大通用人脸数据库上的实验验证了所提方法的有效性,实验结果表明,与最先进的纹理方法相比,所提方法取得了更好的识别性能。