Rong-Xiang Hu

Discriminant sparse neighborhood preserving embedding for face recognition

Sparse subspace learning has drawn more and more attentions recently. However, most of the sparse subspace learning methods are unsupervised and unsuitable for classification tasks. In this paper, a new sparse subspace learning algorithm called discriminant sparse neighborhood preserving embedding (DSNPE) is proposed by adding the discriminant information into sparse neighborhood preserving embedding (SNPE). DSNPE not only preserves the sparse reconstructive relationship of SNPE, but also sufficiently utilizes the global discriminant structures from the following two aspects: (1) maximum margin criterion (MMC) is added into the objective function of DSNPE; (2) only the training samples with the same label as the current sample are used to compute the sparse reconstructive relationship. Extensive experiments on three face image datasets (Yale, Extended Yale B and AR) demonstrate the effectiveness of the proposed DSNPE method.

Completed robust local binary pattern for texture classification

Original Local Binary Pattern (LBP) descriptor has two obvious demerits, i.e., it is sensitive to noise, and sometimes it tends to characterize different structural patterns with the same binary code which will reduce its discriminability inevitably. In order to overcome these two demerits, this paper proposes a robust framework of LBP, named Completed Robust Local Binary Pattern (CRLBP), in which the value of each center pixel in a 3x3 local area is replaced by its average local gray level. Compared to the center gray value, average local gray level is more robust to noise and illumination variants. To make CRLBP more robust and stable, Weighted Local Gray Level (WLG) is introduced to take place of the traditional gray value of the center pixel. The experimental results obtained from four representative texture databases show that the proposed method is robust to noise and can achieve impressive classification accuracy.

Multiscale Distance Matrix for Fast Plant Leaf Recognition

In this brief, we propose a novel contour-based shape descriptor, called the multiscale distance matrix, to capture the shape geometry while being invariant to translation, rotation, scaling, and bilateral symmetry. The descriptor is further combined with a dimensionality reduction to improve its discriminative power. The proposed method avoids the time-consuming pointwise matching encountered in most of the previously used shape recognition algorithms. It is therefore fast and suitable for real-time applications. We applied the proposed method to the task of plan leaf recognition with experiments on two data sets, the Swedish Leaf data set and the ICL Leaf data set. The experimental results clearly demonstrate the effectiveness and efficiency of the proposed descriptor.

An Intensity-Texture model based level set method for image segmentation

In this paper, a novel level set segmentation model integrating the intensity and texture terms is proposed to segment complicated two-phase nature images. Firstly, an intensity term based on the global division algorithm is proposed, which can better capture intensity information of image than the Chan-Vese model (CV). Particularly, the CV model is a special case of the proposed intensity term under a certain condition. Secondly, a texture term based on the adaptive scale local variation degree (ASLVD) algorithm is proposed. The ASLVD algorithm adaptively incorporates the amplitude and frequency components of local intensity variation, thus, it can extract the non-stationary texture feature accurately. Finally, the intensity term and the texture term are jointly incorporated into level set and used to construct effective image segmentation model named as the Intensity-Texture model. Since the intensity term and the texture term are complementary for image segmentation, the Intensity-Texture model has strong ability to accurately segment those complicated two-phase nature images. Experimental results demonstrate the effectiveness of the proposed Intensity-Texture model. An intensity term based on the so-called global division algorithm is proposed.We extract the amplitude and frequency components of local intensity variation.We propose the adaptive scale local variation degree algorithm as texture term.The intensity and texture terms are integrated into level set energy functional.

HOG-based approach for leaf classification

In this paper, we propose a new approach for plant leaf classification, which treat histogram of oriented gradients (HOG) as a new representation of shape, and use the Maximum Margin Criterion (MMC) for dimensionality reduction. We compare this algorithm with a classic shape classification method Inner-Distance Shape Context (IDSC) on Swedish leaf dataset and ICL dataset. The proposed method achieves better performance compared with IDSC.

Maximum margin criterion with tensor representation

In this paper, we propose tensor based Maximum Margin Criterion algorithm (TMMC) for supervised dimensionality reduction. In TMMC, an image object is encoded as an nth-order tensor, and its 2-D representation is directly treated as matrix. Meanwhile, the k-mode optimization approach is exploited to iteratively learn multiple interrelated discriminative subspaces for dimensionality reduction of the higher order tensor. TMMC generalizes the traditional MMC based on vector data to the one based on matrix and tensor data, which completes the MMC family in terms of data representation. The results of experiments conducted on four databases show that the accurate recognition rate of TMMC is better than that of the method of Concurrent Subspaces Analysis (CSA), and is comparable with the method of Multilinear Discriminant Analysis (MDA). The experimental results also show that the accurate recognition rate of the tensor/matrix-based methods may not always be better than that of vector-based methods. Reasonable discussions about this phenomenon have been given in this paper.

Hand shape recognition based on coherent distance shape contexts

In this paper, we propose a novel hand shape recognition method named as Coherent Distance Shape Contexts (CDSC), which is based on two classical shape representations, i.e., Shape Contexts (SC) and Inner-distance Shape Contexts (IDSC). CDSC has good ability to capture discriminative features from hand shape and can well deal with the inexact correspondence problem of hand landmark points. Particularly, it can extract features mainly from the contour of fingers. Thus, it is very robust to different hand poses or elastic deformations of finger valleys. In order to verify the effectiveness of CDSC, we create a new hand image database containing 4000 grayscale left hand images of 200 subjects, on which CDSC has achieved the accurate identification rate of 99.60% for identification and the Equal Error Rate of 0.9% for verification, which are comparable with the state-of-the-art hand shape recognition methods.

Perceptually motivated morphological strategies for shape retrieval

In this paper, two perceptually motivated morphological strategies (PMMS) are proposed to enhance the retrieval performance of common shape matching methods. Firstly, two human perception customs are introduced, which have important relations to shape retrieval. Secondly, these two customs are properly modeled by morphological operations. Finally, the proposed PMMS is applied to improve the retrieval performances of a popular shape matching method named Inner-Distance Shape Contexts (IDSC), and then the Locally Constrained Diffusion Process (LCDP) method is exploited to further enhance the retrieval performance. This combination achieves a retrieval rate of 98.56% on MPEG-7 dataset. We also conduct the experiments on Swedish Leaf dataset, the ETH-80 dataset and the Natural Silhouette dataset. The experimental results obtained from four datasets demonstrate clearly the effectiveness of the proposed method.

Angular Pattern and Binary Angular Pattern for Shape Retrieval

In this paper, we propose two novel shape descriptors, angular pattern (AP) and binary angular pattern (BAP), and a multiscale integration of them for shape retrieval. Both AP and BAP are intrinsically invariant to scale and rotation. More importantly, being global shape descriptors, the proposed shape descriptors are computationally very efficient, while possessing similar discriminability as state-of-the-art local descriptors. As a result, the proposed approach is attractive for real world shape retrieval applications. The experiments on the widely used MPEG-7 and TARI-1000 data sets demonstrate the effectiveness of the proposed method in comparison with existing methods.

Newborn footprint recognition using orientation feature

Newborn and infant personal authentication is a critical issue for hospital, birthing centers, and other institutions where multiple births occur, which has not been well studied in the past. In this paper, we propose a novel online newborn personal authentication system for this issue based on footprint recognition. Compared with traditional offline footprinting scheme, the proposed system can capture digital footprint images with high quality. We also develop a preprocessing method for orientation and scale normalization. In this way, a coordinate system is defined to align the images, and a region of interest (ROI) is cropped. In recognition stage, four orientation feature-based approaches, Ordinal Code, BOCV, Competitive Code, and Robust Line Orientation Code, are exploited for recognition. A newborn footprint database is established to examine the performance of the proposed system, and promising experimental results demonstrate the effectiveness of the proposed system.