Italy

In the recognition problem, a canonical form that
expresses the spatio-temporal relation of concepts for a given
class can potentially increase accuracy. Concepts are defined as
attributes that can be recognized using a soft matching paradigm.
We consider the specific case study of American Sign Language
(ASL) to show that canonical forms of classes can be used to
recognize unseen gestures. There are several advantages of a
canonical form of gestures including translation between gestures,
gesture-based searching, and automated transcription of gestures
into any spoken language. We applied our technique to two
independently collected datasets: a) IMPACT Lab dataset: 23
ASL gestures each executed three times from 130 first time ASL
learners as training data and b) ASLTEXT dataset: 190 gestures
each executed six times on an average. Our technique was able to
recognize 19 arbitrarily chosen previously unseen gestures in the
IMPACT dataset from seven individuals who are not a part of 130
and 34 unseen gestures from the ASLTEXT dataset without any
retraining. Our normalized accuracy on the ASLTEXT dataset
is 66% which is 13.6 % higher than the state-of-art technique.

ICPR 2020

Concept Embedding through Canonical Forms: A Case Study on Zero-Shot American Sign Language Recognition

language processing

zero shot learning

gesture recognition

ICPR 2020 is the premier international conference on Pattern Recognition, gathering leading researchers from around the world to present their latest achievements in Pattern Analysis and Recognition, applied Artificial Intelligence and Machine Learning. The topic of the year is " Putting Artificial intelligence to work on Patterns". 
For the first time, ICPR has employed a two-round review process similar to journal submissions, with new papers allowed to be submitted in either the first or second round and papers submitted in the first round and not accepted allowed to be revised and re-submitted for second round review. 

In this edition of the **ICPR 2020** Conference, there are 1407 Oral/Poster presentations organized in five Tracks: 
- Artificial Intelligence, Machine Learning for Pattern Analysis; 
- Biometrics, Human Analysis and Behavior Understanding; Computer Vision, Robotics and Intelligent Systems; 
- Document and Media Analysis; and 
- Image and Signal Processing. 

The **ICPR 2020** Main Conference program also includes 7 Keynotes from prominent world-renowned scientists, 8 Tutorials, 28 Demos, 8 Challenges, 2 Panels, as well as an Industry/Sponsor Exhibition. In addition, 41 Workshops on a range of important current and emerging research topics complete the ICPR 2020 program. 


poster

In this paper, we propose the use of Optical Coherence
Tomography (OCT) imaging for the problem of iris
presentation attack (PA) detection. We assess its viability by
comparing its performance with respect to traditional iris imaging
modalities, viz., near-infrared (NIR) and visible spectrum.
OCT imaging provides a cross-sectional view of an eye, whereas
traditional imaging provides 2D iris textural information. PA
detection is performed using three state-of-the-art deep architectures
(VGG19, ResNet50 and DenseNet121) to differentiate
between bonafide and PA samples for each of the three imaging
modalities. Experiments are performed on a dataset of 2,169
bonafide, 177 Van Dyke eyes and 360 cosmetic contact images
acquired using all three imaging modalities under intra-attack
(known PAs) and cross-attack (unknown PAs) scenarios. We
observe promising results demonstrating OCT as a viable solution
for iris presentation attack detection.

Viability of Optical Coherence Tomography for Iris Presentation Attack Detection


In this work, we tackle the problem of estimating a camera capability to preserve fine texture details at a given lighting condition. Importantly, our texture preservation measurement should coincide with human perception. Consequently, we formulate our problem as a regression one and we introduce a deep convolutional network to estimate texture quality score. At training time, we use ground-truth quality scores provided by expert human annotators in order to obtain a subjective quality measure. In addition, we propose a region selection method to identify the image regions that are better suited at measuring perceptual quality. Finally, our experimental evaluation shows that our learning-based approach outperforms existing methods and that our region selection algorithm consistently improves the quality estimation.

DR2S: Deep Regression with Region Selection for Camera Quality Evaluation

Class imbalance limits the performance of most learning algorithms, resulting in a low recognition rate for samples belonging to the minority class. Although there are different strategies to address this problem, methods that generate ensemble of classifiers have proven to be effective in several applications. This paper presents a new strategy to construct the training set of each classifier in the ensemble by exploiting information in the feature space that can give rise to unreliable classifications, which are determined by a novel algorithm here introduced. The performance of our proposal is compared against multiple standard ensemble approaches on 25 publicly available datasets, showing promising results.

Categorizing the feature space for two-class imbalance learning


Medical image segmentation has played an important
role in medical analysis and widely developed for many clinical
applications. Deep learning-based approaches have achieved
high performance in semantic segmentation but they are limited
to pixel-wise setting and imbalanced classes data problem. In
this paper, we tackle those limitations by developing a new
deep learning-based model which takes into account both higher
feature level i.e. region inside contour, intermediate feature level
i.e. offset curves around the contour and lower feature level i.e.
contour. Our proposed Offset Curves (OsC) loss consists of three
main fitting terms. The first fitting term focuses on pixel-wise level
segmentation whereas the second fitting term acts as attention
model which pays attention to the area around the boundaries
(offset curves). The third terms plays a role as regularization
term which takes the length of boundaries into account. We
evaluate our proposed OsC loss on both 2D network and 3D
network. Two common medical datasets, i.e. retina DRIVE and
brain tumor BRATS 2018 datasets are used to benchmark our
proposed loss performance. The experiments have shown that
our proposed OsC loss function outperforms other mainstream
loss functions such as Cross-Entropy, Dice, Focal on the most
common segmentation networks Unet, FCN.

Offset Curves Loss for Imbalanced Problem in Medical Segmentation

Anomaly detection in complex data structures is one of the most challenging problems in computer vision. In many real-world problems, for example in the quality control in modern manufacturing, the anomalous samples are usually rare, resulting in (highly) imbalanced datasets. However, in current research practice, these scenarios are rarely modeled, and as a consequence, evaluation of anomaly detection algorithms often do not reproduce results that are useful for practical applications. First, even in case of highly unbalanced input data, anomaly detection algorithms are expected to significantly reduce the proportion of anomalous samples, detecting ”almost all” anomalous samples (with exact specifications depending on the target customer). This places high importance on only the small part of the ROC curve, possibly rendering the standard metrics such as AUC (Area Under Curve) and AP (Average Precision) useless. Second, the target of automatic anomaly detection in practical applications is the significant reduction in manual work required, and standard metrics are poor predictor of this feature. Finally, the evaluation may produce erratic results for different randomly initialized training runs of the neural network, producing evaluation results that may not reproduce well in practice. In our presentation, we present an evaluation methodology that avoids these pitfalls.

Evaluation of Anomaly Detection Algorithms for the Real-world Applications

One of the most computationally intensive parts in modern recognition systems is an inference of deep neural networks that are used for image classification, segmentation, enhancement, and recognition. The growing popularity of edge computing makes us look for ways to reduce its time for mobile and embedded devices. One way to decrease the neural network inference time is to modify a neuron model to make it more efficient for computations on a specific device. The example of such a model is a bipolar morphological neuron model. The bipolar morphological neuron is based on the idea of replacing multiplication with addition and maximum operations. This model has been demonstrated for simple image classification with LeNet-like architectures [1]. In the paper, we introduce a bipolar morphological ResNet (BM-ResNet) model obtained from a much more complex ResNet architecture by converting its layers to bipolar morphological ones. We apply BM-ResNet to image classification on MNIST and CIFAR-10 datasets with only a moderate accuracy decrease from 99.3% to 99.1% and from 85.3% to 85.1%. We also estimate the computational complexity of the resulting model. We show that for the majority of ResNet layers, the considered model requires 2.1-2.9 times fewer logic gates for implementation and 15-30% lower latency.

ResNet-like Architecture with Low Hardware Requirements

Stochastic block models (SBMs) are often used to find assortative community structures in networks, such that the probability of connections within communities is higher than in between communities. However, classic SBMs are not limited to assortative structures. In this study, we discuss the implications of this model-inherent indifference towards assortativity or disassortativity, and show that this characteristic can lead to undesirable outcomes for networks which are presupposedy assortative but which contain a reduced amount of information. To circumvent this issue, we introduce a constrained SBM that imposes strong assortativity constraints, along with efficient algorithmic approaches to solve it. These constraints significantly boost community recovery capabilities in regimes that are close to the information-theoretic threshold. They also permit to identify structurally-different communities in networks representing cerebral-cortex activity regions.

Assortative-Constrained Stochastic Block Models

In this paper we ask for the main factors that determine a classifier's decision making process and uncover such factors by studying latent codes produced by auto-encoding frameworks. To deliver an explanation of a classifier's behaviour, we propose a method that provides series of examples highlighting semantic differences between the classifier's decisions. These examples are generated through interpolations in latent space. We introduce and formalize the notion of a semantic stochastic path, as a suitable stochastic process defined in feature (data) space via latent code interpolations. We then introduce the concept of semantic Lagrangians as a way to incorporate the desired classifier's behaviour and find that the solution of the associated variational problem allows for highlighting differences in the classifier decision.
Very importantly, within our framework the classifier is used as a black-box, and only its evaluation is required.

Auto Encoding Explanatory Examples with Stochastic Paths


Morphological hierarchies form a popular framework aiming at emphasizing the multiscale structure of digital image by performing an unsupervised spatial partitioning of the data. These hierarchies have been recently extended to cope with image sequences, and different strategies have been proposed to allow their construction from spatio-temporal data. In this paper, we compare these hierarchical representation strategies for image sequences according to their structural properties. We introduce a projection method to make these representations comparable. Furthermore, we extend one of these recent strategies in order to obtain more efficient hierarchical representations for image sequences. Experiments were conducted on both synthetic and real datasets, the latter being made of satellite image time series. We show that building one hierarchy by using spatial and temporal information together is more efficient comparing to other existing strategies.

On Morphological Hierarchies for Image Sequences


This paper studies the problem of Person Re-Identification (ReID)
for large-scale applications. Recent research efforts have been devoted
to building complicated part models, which introduce considerably
high computational cost and memory consumption, inhibiting its practicability
in large-scale applications. This paper aims to develop a novel learning
strategy to find efficient feature embeddings while maintaining the
balance of accuracy and model complexity. More specifically, we find
by enhancing the classical triplet loss together with cross-entropy
loss, our method can explore the hard examples and build a discriminant
feature embedding yet compact enough for large-scale applications.
Our method is carried out progressively using Bayesian optimization,
and we call it the Progressive Learning Algorithm (PLA). Extensive
experiments on three large-scale datasets show that our PLA is comparable
or better than the state-of-the-arts. Especially, on the challenging
Market-1501 dataset, we achieve Rank-1=94.7%/mAP=89.4% while saving
at least 30\% parameters than strong part models.

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Concept Embedding through Canonical Forms: A Case Study on Zero-Shot American Sign Language Recognition

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