12 research outputs found
Fast Low-rank Representation based Spatial Pyramid Matching for Image Classification
Spatial Pyramid Matching (SPM) and its variants have achieved a lot of
success in image classification. The main difference among them is their
encoding schemes. For example, ScSPM incorporates Sparse Code (SC) instead of
Vector Quantization (VQ) into the framework of SPM. Although the methods
achieve a higher recognition rate than the traditional SPM, they consume more
time to encode the local descriptors extracted from the image. In this paper,
we propose using Low Rank Representation (LRR) to encode the descriptors under
the framework of SPM. Different from SC, LRR considers the group effect among
data points instead of sparsity. Benefiting from this property, the proposed
method (i.e., LrrSPM) can offer a better performance. To further improve the
generalizability and robustness, we reformulate the rank-minimization problem
as a truncated projection problem. Extensive experimental studies show that
LrrSPM is more efficient than its counterparts (e.g., ScSPM) while achieving
competitive recognition rates on nine image data sets.Comment: accepted into knowledge based systems, 201
Kernel Truncated Regression Representation for Robust Subspace Clustering
Subspace clustering aims to group data points into multiple clusters of which
each corresponds to one subspace. Most existing subspace clustering approaches
assume that input data lie on linear subspaces. In practice, however, this
assumption usually does not hold. To achieve nonlinear subspace clustering, we
propose a novel method, called kernel truncated regression representation. Our
method consists of the following four steps: 1) projecting the input data into
a hidden space, where each data point can be linearly represented by other data
points; 2) calculating the linear representation coefficients of the data
representations in the hidden space; 3) truncating the trivial coefficients to
achieve robustness and block-diagonality; and 4) executing the graph cutting
operation on the coefficient matrix by solving a graph Laplacian problem. Our
method has the advantages of a closed-form solution and the capacity of
clustering data points that lie on nonlinear subspaces. The first advantage
makes our method efficient in handling large-scale datasets, and the second one
enables the proposed method to conquer the nonlinear subspace clustering
challenge. Extensive experiments on six benchmarks demonstrate the
effectiveness and the efficiency of the proposed method in comparison with
current state-of-the-art approaches.Comment: 14 page
Contrastive Clustering
In this paper, we propose a one-stage online clustering method called
Contrastive Clustering (CC) which explicitly performs the instance- and
cluster-level contrastive learning. To be specific, for a given dataset, the
positive and negative instance pairs are constructed through data augmentations
and then projected into a feature space. Therein, the instance- and
cluster-level contrastive learning are respectively conducted in the row and
column space by maximizing the similarities of positive pairs while minimizing
those of negative ones. Our key observation is that the rows of the feature
matrix could be regarded as soft labels of instances, and accordingly the
columns could be further regarded as cluster representations. By simultaneously
optimizing the instance- and cluster-level contrastive loss, the model jointly
learns representations and cluster assignments in an end-to-end manner.
Extensive experimental results show that CC remarkably outperforms 17
competitive clustering methods on six challenging image benchmarks. In
particular, CC achieves an NMI of 0.705 (0.431) on the CIFAR-10 (CIFAR-100)
dataset, which is an up to 19\% (39\%) performance improvement compared with
the best baseline
Joint Group Feature Selection and Discriminative Filter Learning for Robust Visual Object Tracking
We propose a new Group Feature Selection method for Discriminative
Correlation Filters (GFS-DCF) based visual object tracking. The key innovation
of the proposed method is to perform group feature selection across both
channel and spatial dimensions, thus to pinpoint the structural relevance of
multi-channel features to the filtering system. In contrast to the widely used
spatial regularisation or feature selection methods, to the best of our
knowledge, this is the first time that channel selection has been advocated for
DCF-based tracking. We demonstrate that our GFS-DCF method is able to
significantly improve the performance of a DCF tracker equipped with deep
neural network features. In addition, our GFS-DCF enables joint feature
selection and filter learning, achieving enhanced discrimination and
interpretability of the learned filters.
To further improve the performance, we adaptively integrate historical
information by constraining filters to be smooth across temporal frames, using
an efficient low-rank approximation. By design, specific
temporal-spatial-channel configurations are dynamically learned in the tracking
process, highlighting the relevant features, and alleviating the performance
degrading impact of less discriminative representations and reducing
information redundancy. The experimental results obtained on OTB2013, OTB2015,
VOT2017, VOT2018 and TrackingNet demonstrate the merits of our GFS-DCF and its
superiority over the state-of-the-art trackers. The code is publicly available
at https://github.com/XU-TIANYANG/GFS-DCF