47 research outputs found
Weakly supervised segment annotation via expectation kernel density estimation
Since the labelling for the positive images/videos is ambiguous in weakly
supervised segment annotation, negative mining based methods that only use the
intra-class information emerge. In these methods, negative instances are
utilized to penalize unknown instances to rank their likelihood of being an
object, which can be considered as a voting in terms of similarity. However,
these methods 1) ignore the information contained in positive bags, 2) only
rank the likelihood but cannot generate an explicit decision function. In this
paper, we propose a voting scheme involving not only the definite negative
instances but also the ambiguous positive instances to make use of the extra
useful information in the weakly labelled positive bags. In the scheme, each
instance votes for its label with a magnitude arising from the similarity, and
the ambiguous positive instances are assigned soft labels that are iteratively
updated during the voting. It overcomes the limitations of voting using only
the negative bags. We also propose an expectation kernel density estimation
(eKDE) algorithm to gain further insight into the voting mechanism.
Experimental results demonstrate the superiority of our scheme beyond the
baselines.Comment: 9 pages, 2 figure
Bag-Level Aggregation for Multiple Instance Active Learning in Instance Classification Problems
A growing number of applications, e.g. video surveillance and medical image
analysis, require training recognition systems from large amounts of weakly
annotated data while some targeted interactions with a domain expert are
allowed to improve the training process. In such cases, active learning (AL)
can reduce labeling costs for training a classifier by querying the expert to
provide the labels of most informative instances. This paper focuses on AL
methods for instance classification problems in multiple instance learning
(MIL), where data is arranged into sets, called bags, that are weakly labeled.
Most AL methods focus on single instance learning problems. These methods are
not suitable for MIL problems because they cannot account for the bag structure
of data. In this paper, new methods for bag-level aggregation of instance
informativeness are proposed for multiple instance active learning (MIAL). The
\textit{aggregated informativeness} method identifies the most informative
instances based on classifier uncertainty, and queries bags incorporating the
most information. The other proposed method, called \textit{cluster-based
aggregative sampling}, clusters data hierarchically in the instance space. The
informativeness of instances is assessed by considering bag labels, inferred
instance labels, and the proportion of labels that remain to be discovered in
clusters. Both proposed methods significantly outperform reference methods in
extensive experiments using benchmark data from several application domains.
Results indicate that using an appropriate strategy to address MIAL problems
yields a significant reduction in the number of queries needed to achieve the
same level of performance as single instance AL methods
An improved image segmentation algorithm for salient object detection
Semantic object detection is one of the most important and challenging problems in image analysis. Segmentation is an optimal approach to detect salient objects, but often fails to generate meaningful regions due to over-segmentation. This paper presents an improved semantic segmentation approach which is based on JSEG algorithm and utilizes multiple region merging criteria. The experimental results demonstrate that the proposed algorithm is encouraging and effective in salient object detection
A Multiple Component Matching Framework for Person Re-Identification
Person re-identification consists in recognizing an individual that has
already been observed over a network of cameras. It is a novel and challenging
research topic in computer vision, for which no reference framework exists yet.
Despite this, previous works share similar representations of human body based
on part decomposition and the implicit concept of multiple instances. Building
on these similarities, we propose a Multiple Component Matching (MCM) framework
for the person re-identification problem, which is inspired by Multiple
Component Learning, a framework recently proposed for object detection. We show
that previous techniques for person re-identification can be considered
particular implementations of our MCM framework. We then present a novel person
re-identification technique as a direct, simple implementation of our
framework, focused in particular on robustness to varying lighting conditions,
and show that it can attain state of the art performances.Comment: Accepted paper, 16th Int. Conf. on Image Analysis and Processing
(ICIAP 2011), Ravenna, Italy, 14/09/201
Multi-view multi-instance learning based on joint sparse representation and multi-view dictionary learning
In multi-instance learning (MIL), the relations among instances in a bag convey important contextual information in many
applications. Previous studies on MIL either ignore such relations or simply model them with a fixed graph structure so that the overall
performance inevitably degrades in complex environments. To address this problem, this paper proposes a novel multi-view
multi-instance learning algorithm (M2IL) that combines multiple context structures in a bag into a unified framework. The novel aspects
are: (i) we propose a sparse "-graph model that can generate different graphs with different parameters to represent various context
relations in a bag, (ii) we propose a multi-view joint sparse representation that integrates these graphs into a unified framework for bag
classification, and (iii) we propose a multi-view dictionary learning algorithm to obtain a multi-view graph dictionary that considers cues
from all views simultaneously to improve the discrimination of the M2IL. Experiments and analyses in many practical applications prove
the effectiveness of the M2IL
On Classification with Bags, Groups and Sets
Many classification problems can be difficult to formulate directly in terms
of the traditional supervised setting, where both training and test samples are
individual feature vectors. There are cases in which samples are better
described by sets of feature vectors, that labels are only available for sets
rather than individual samples, or, if individual labels are available, that
these are not independent. To better deal with such problems, several
extensions of supervised learning have been proposed, where either training
and/or test objects are sets of feature vectors. However, having been proposed
rather independently of each other, their mutual similarities and differences
have hitherto not been mapped out. In this work, we provide an overview of such
learning scenarios, propose a taxonomy to illustrate the relationships between
them, and discuss directions for further research in these areas