2,746 research outputs found
Multiple Instance Learning: A Survey of Problem Characteristics and Applications
Multiple instance learning (MIL) is a form of weakly supervised learning
where training instances are arranged in sets, called bags, and a label is
provided for the entire bag. This formulation is gaining interest because it
naturally fits various problems and allows to leverage weakly labeled data.
Consequently, it has been used in diverse application fields such as computer
vision and document classification. However, learning from bags raises
important challenges that are unique to MIL. This paper provides a
comprehensive survey of the characteristics which define and differentiate the
types of MIL problems. Until now, these problem characteristics have not been
formally identified and described. As a result, the variations in performance
of MIL algorithms from one data set to another are difficult to explain. In
this paper, MIL problem characteristics are grouped into four broad categories:
the composition of the bags, the types of data distribution, the ambiguity of
instance labels, and the task to be performed. Methods specialized to address
each category are reviewed. Then, the extent to which these characteristics
manifest themselves in key MIL application areas are described. Finally,
experiments are conducted to compare the performance of 16 state-of-the-art MIL
methods on selected problem characteristics. This paper provides insight on how
the problem characteristics affect MIL algorithms, recommendations for future
benchmarking and promising avenues for research
Efficient contour-based shape representation and matching
This paper presents an efficient method for calculating the
similarity between 2D closed shape contours. The proposed
algorithm is invariant to translation, scale change and rotation. It can be used for database retrieval or for detecting regions with a particular shape in video sequences. The proposed algorithm is suitable for real-time applications. In the first stage of the algorithm, an ordered sequence of contour points approximating the shapes is extracted from the input binary images. The contours are translation and scale-size normalized, and small sets of the most likely starting points for both shapes are extracted. In the second stage, the starting points from both shapes are assigned into pairs and rotation alignment is performed. The dissimilarity measure is based on the geometrical distances between corresponding contour points. A fast sub-optimal method for solving the correspondence problem between contour points from two shapes is proposed. The dissimilarity measure is calculated for each pair of starting points. The lowest dissimilarity is taken as the final dissimilarity measure between two shapes. Three different experiments are carried out using the proposed
approach: letter recognition using a web camera, our
own simulation of Part B of the MPEG-7 core experiment
“CE-Shape1” and detection of characters in cartoon video
sequences. Results indicate that the proposed dissimilarity
measure is aligned with human intuition
3D Shape Classification and Retrieval Using Heterogenous Features and Supervised Learning
Content-based 3D model retrieval (CB3DMR) aims at augmenting the text-based search with the ability to search 3D data collections by using examples, sketches, as well as geometric and structural features..
Deep Shape Matching
We cast shape matching as metric learning with convolutional networks. We
break the end-to-end process of image representation into two parts. Firstly,
well established efficient methods are chosen to turn the images into edge
maps. Secondly, the network is trained with edge maps of landmark images, which
are automatically obtained by a structure-from-motion pipeline. The learned
representation is evaluated on a range of different tasks, providing
improvements on challenging cases of domain generalization, generic
sketch-based image retrieval or its fine-grained counterpart. In contrast to
other methods that learn a different model per task, object category, or
domain, we use the same network throughout all our experiments, achieving
state-of-the-art results in multiple benchmarks.Comment: ECCV 201
Hierarchical Deep Learning Architecture For 10K Objects Classification
Evolution of visual object recognition architectures based on Convolutional
Neural Networks & Convolutional Deep Belief Networks paradigms has
revolutionized artificial Vision Science. These architectures extract & learn
the real world hierarchical visual features utilizing supervised & unsupervised
learning approaches respectively. Both the approaches yet cannot scale up
realistically to provide recognition for a very large number of objects as high
as 10K. We propose a two level hierarchical deep learning architecture inspired
by divide & conquer principle that decomposes the large scale recognition
architecture into root & leaf level model architectures. Each of the root &
leaf level models is trained exclusively to provide superior results than
possible by any 1-level deep learning architecture prevalent today. The
proposed architecture classifies objects in two steps. In the first step the
root level model classifies the object in a high level category. In the second
step, the leaf level recognition model for the recognized high level category
is selected among all the leaf models. This leaf level model is presented with
the same input object image which classifies it in a specific category. Also we
propose a blend of leaf level models trained with either supervised or
unsupervised learning approaches. Unsupervised learning is suitable whenever
labelled data is scarce for the specific leaf level models. Currently the
training of leaf level models is in progress; where we have trained 25 out of
the total 47 leaf level models as of now. We have trained the leaf models with
the best case top-5 error rate of 3.2% on the validation data set for the
particular leaf models. Also we demonstrate that the validation error of the
leaf level models saturates towards the above mentioned accuracy as the number
of epochs are increased to more than sixty.Comment: As appeared in proceedings for CS & IT 2015 - Second International
Conference on Computer Science & Engineering (CSEN 2015
Deep Learning Face Attributes in the Wild
Predicting face attributes in the wild is challenging due to complex face
variations. We propose a novel deep learning framework for attribute prediction
in the wild. It cascades two CNNs, LNet and ANet, which are fine-tuned jointly
with attribute tags, but pre-trained differently. LNet is pre-trained by
massive general object categories for face localization, while ANet is
pre-trained by massive face identities for attribute prediction. This framework
not only outperforms the state-of-the-art with a large margin, but also reveals
valuable facts on learning face representation.
(1) It shows how the performances of face localization (LNet) and attribute
prediction (ANet) can be improved by different pre-training strategies.
(2) It reveals that although the filters of LNet are fine-tuned only with
image-level attribute tags, their response maps over entire images have strong
indication of face locations. This fact enables training LNet for face
localization with only image-level annotations, but without face bounding boxes
or landmarks, which are required by all attribute recognition works.
(3) It also demonstrates that the high-level hidden neurons of ANet
automatically discover semantic concepts after pre-training with massive face
identities, and such concepts are significantly enriched after fine-tuning with
attribute tags. Each attribute can be well explained with a sparse linear
combination of these concepts.Comment: To appear in International Conference on Computer Vision (ICCV) 201
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