12,243 research outputs found
Image Aesthetics Assessment Using Composite Features from off-the-Shelf Deep Models
Deep convolutional neural networks have recently achieved great success on
image aesthetics assessment task. In this paper, we propose an efficient method
which takes the global, local and scene-aware information of images into
consideration and exploits the composite features extracted from corresponding
pretrained deep learning models to classify the derived features with support
vector machine. Contrary to popular methods that require fine-tuning or
training a new model from scratch, our training-free method directly takes the
deep features generated by off-the-shelf models for image classification and
scene recognition. Also, we analyzed the factors that could influence the
performance from two aspects: the architecture of the deep neural network and
the contribution of local and scene-aware information. It turns out that deep
residual network could produce more aesthetics-aware image representation and
composite features lead to the improvement of overall performance. Experiments
on common large-scale aesthetics assessment benchmarks demonstrate that our
method outperforms the state-of-the-art results in photo aesthetics assessment.Comment: Accepted by ICIP 201
Performance Guarantees for Distributed Reachability Queries
In the real world a graph is often fragmented and distributed across
different sites. This highlights the need for evaluating queries on distributed
graphs. This paper proposes distributed evaluation algorithms for three classes
of queries: reachability for determining whether one node can reach another,
bounded reachability for deciding whether there exists a path of a bounded
length between a pair of nodes, and regular reachability for checking whether
there exists a path connecting two nodes such that the node labels on the path
form a string in a given regular expression. We develop these algorithms based
on partial evaluation, to explore parallel computation. When evaluating a query
Q on a distributed graph G, we show that these algorithms possess the following
performance guarantees, no matter how G is fragmented and distributed: (1) each
site is visited only once; (2) the total network traffic is determined by the
size of Q and the fragmentation of G, independent of the size of G; and (3) the
response time is decided by the largest fragment of G rather than the entire G.
In addition, we show that these algorithms can be readily implemented in the
MapReduce framework. Using synthetic and real-life data, we experimentally
verify that these algorithms are scalable on large graphs, regardless of how
the graphs are distributed.Comment: VLDB201
Feature Augmentation via Nonparametrics and Selection (FANS) in High Dimensional Classification
We propose a high dimensional classification method that involves
nonparametric feature augmentation. Knowing that marginal density ratios are
the most powerful univariate classifiers, we use the ratio estimates to
transform the original feature measurements. Subsequently, penalized logistic
regression is invoked, taking as input the newly transformed or augmented
features. This procedure trains models equipped with local complexity and
global simplicity, thereby avoiding the curse of dimensionality while creating
a flexible nonlinear decision boundary. The resulting method is called Feature
Augmentation via Nonparametrics and Selection (FANS). We motivate FANS by
generalizing the Naive Bayes model, writing the log ratio of joint densities as
a linear combination of those of marginal densities. It is related to
generalized additive models, but has better interpretability and computability.
Risk bounds are developed for FANS. In numerical analysis, FANS is compared
with competing methods, so as to provide a guideline on its best application
domain. Real data analysis demonstrates that FANS performs very competitively
on benchmark email spam and gene expression data sets. Moreover, FANS is
implemented by an extremely fast algorithm through parallel computing.Comment: 30 pages, 2 figure
Are Discoveries Spurious? Distributions of Maximum Spurious Correlations and Their Applications
Over the last two decades, many exciting variable selection methods have been
developed for finding a small group of covariates that are associated with the
response from a large pool. Can the discoveries from these data mining
approaches be spurious due to high dimensionality and limited sample size? Can
our fundamental assumptions about the exogeneity of the covariates needed for
such variable selection be validated with the data? To answer these questions,
we need to derive the distributions of the maximum spurious correlations given
a certain number of predictors, namely, the distribution of the correlation of
a response variable with the best linear combinations of covariates
, even when and are independent. When the
covariance matrix of possesses the restricted eigenvalue property,
we derive such distributions for both a finite and a diverging , using
Gaussian approximation and empirical process techniques. However, such a
distribution depends on the unknown covariance matrix of . Hence,
we use the multiplier bootstrap procedure to approximate the unknown
distributions and establish the consistency of such a simple bootstrap
approach. The results are further extended to the situation where the residuals
are from regularized fits. Our approach is then used to construct the upper
confidence limit for the maximum spurious correlation and to test the
exogeneity of the covariates. The former provides a baseline for guarding
against false discoveries and the latter tests whether our fundamental
assumptions for high-dimensional model selection are statistically valid. Our
techniques and results are illustrated with both numerical examples and real
data analysis
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