38,659 research outputs found
Hashing for Similarity Search: A Survey
Similarity search (nearest neighbor search) is a problem of pursuing the data
items whose distances to a query item are the smallest from a large database.
Various methods have been developed to address this problem, and recently a lot
of efforts have been devoted to approximate search. In this paper, we present a
survey on one of the main solutions, hashing, which has been widely studied
since the pioneering work locality sensitive hashing. We divide the hashing
algorithms two main categories: locality sensitive hashing, which designs hash
functions without exploring the data distribution and learning to hash, which
learns hash functions according the data distribution, and review them from
various aspects, including hash function design and distance measure and search
scheme in the hash coding space
Evaluation of Hashing Methods Performance on Binary Feature Descriptors
In this paper we evaluate performance of data-dependent hashing methods on
binary data. The goal is to find a hashing method that can effectively produce
lower dimensional binary representation of 512-bit FREAK descriptors. A
representative sample of recent unsupervised, semi-supervised and supervised
hashing methods was experimentally evaluated on large datasets of labelled
binary FREAK feature descriptors
Usability of Humanly Computable Passwords
Reusing passwords across multiple websites is a common practice that
compromises security. Recently, Blum and Vempala have proposed password
strategies to help people calculate, in their heads, passwords for different
sites without dependence on third-party tools or external devices. Thus far,
the security and efficiency of these "mental algorithms" has been analyzed only
theoretically. But are such methods usable? We present the first usability
study of humanly computable password strategies, involving a learning phase (to
learn a password strategy), then a rehearsal phase (to login to a few
websites), and multiple follow-up tests. In our user study, with training,
participants were able to calculate a deterministic eight-character password
for an arbitrary new website in under 20 seconds
Deep Hashing Network for Unsupervised Domain Adaptation
In recent years, deep neural networks have emerged as a dominant machine
learning tool for a wide variety of application domains. However, training a
deep neural network requires a large amount of labeled data, which is an
expensive process in terms of time, labor and human expertise. Domain
adaptation or transfer learning algorithms address this challenge by leveraging
labeled data in a different, but related source domain, to develop a model for
the target domain. Further, the explosive growth of digital data has posed a
fundamental challenge concerning its storage and retrieval. Due to its storage
and retrieval efficiency, recent years have witnessed a wide application of
hashing in a variety of computer vision applications. In this paper, we first
introduce a new dataset, Office-Home, to evaluate domain adaptation algorithms.
The dataset contains images of a variety of everyday objects from multiple
domains. We then propose a novel deep learning framework that can exploit
labeled source data and unlabeled target data to learn informative hash codes,
to accurately classify unseen target data. To the best of our knowledge, this
is the first research effort to exploit the feature learning capabilities of
deep neural networks to learn representative hash codes to address the domain
adaptation problem. Our extensive empirical studies on multiple transfer tasks
corroborate the usefulness of the framework in learning efficient hash codes
which outperform existing competitive baselines for unsupervised domain
adaptation.Comment: CVPR 201
Learning to Hash-tag Videos with Tag2Vec
User-given tags or labels are valuable resources for semantic understanding
of visual media such as images and videos. Recently, a new type of labeling
mechanism known as hash-tags have become increasingly popular on social media
sites. In this paper, we study the problem of generating relevant and useful
hash-tags for short video clips. Traditional data-driven approaches for tag
enrichment and recommendation use direct visual similarity for label transfer
and propagation. We attempt to learn a direct low-cost mapping from video to
hash-tags using a two step training process. We first employ a natural language
processing (NLP) technique, skip-gram models with neural network training to
learn a low-dimensional vector representation of hash-tags (Tag2Vec) using a
corpus of 10 million hash-tags. We then train an embedding function to map
video features to the low-dimensional Tag2vec space. We learn this embedding
for 29 categories of short video clips with hash-tags. A query video without
any tag-information can then be directly mapped to the vector space of tags
using the learned embedding and relevant tags can be found by performing a
simple nearest-neighbor retrieval in the Tag2Vec space. We validate the
relevance of the tags suggested by our system qualitatively and quantitatively
with a user study
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