Talk: Leveraging Spatial, Spectral and Temporal Features for Spoofing Detection in Images and Videos

Being part of a series of four talks that will be given at NTU Singapore, in this second talk Prof. Anderson Rocha (RECOD) will explore the research field of Spoofing Detection in Images and Videos.

Abstract: Recent advances on biometrics, information forensics, and security have improved the recognition effectiveness of facial biometric systems. However, an ever-growing challenge is the vulnerability of such systems to spoofing attacks, in which impostor users create synthetic samples from original biometric information of a valid user and show them to the biometric system seeking to authenticate themselves as valid users. Depending on the trait used by the biometric systems, the type of attack varies with the type of material used to build the synthetic samples. For instance, in facial biometric systems, an attempted attack is characterized by the type of material the impostor uses such as a photograph, a digital video, or a 3-D mask with the facial information of a target user. In iris-based biometrics, spoofing attempts can be performed with printed photo or with contact lenses containing the iris patterns of a target user. Finally, fingerprint biometric systems can be spoofed by an impostor user in possession of replicas of the fingerprint patterns built with materials such as latex, play-doh, silicone, among other. In this talk, we will present anti-spoofing solutions whose objective is to detect attempted attacks considering these different types of attacks, in each modality. The lines of investigation include devising and developing visual representations based on spatial, temporal and spectral information and deep learning techniques.

Date: 22 Feb 2017, Wednesday

Time: 2.00pm – 3.00 pm (Seated by 1.50pm)

Venue: Demo Room, ROSE Lab, Research Techno Plaza (RTP), Level 4, Border X Block, 50 Nanyang Drive, 637553

Posted in blog, Keynotes, science, talk | Tagged , , , , | Leave a comment

A graph-based ranked-list model for unsupervised distance learning on shape retrieval

Overview of the proposed Ranked-List Graph model

Overview of the proposed Ranked-List Graph model

Several re-ranking algorithms have been proposed recently. Some effective approaches are based on complex graph-based diffusion processes, which usually are time consuming and therefore inappro- priate for real-world large scale shape collections.

In this article, the authors present a novel rank-based algorithm for improving the effectiveness of shape retrieval tasks. The algorithm models each ranked list as a graph, establishing similarity connections among all top-k images. Next, a graph fusion approach is employed for obtaining a single graph representing the whole collection and exploiting the relationships encoded in the dataset manifold. Based on the fused graph, a new distance is learned and a new set of ranked lists is computed. The effectiveness of the proposed approach is demonstrated by the performance of an extensive experimental protocol considering widely used shape collections.


Daniel Carlos Guimarães Pedronette, Jurandy Almeida, Ricardo da S. Torres, A graph-based ranked-list model for unsupervised distance learning on shape retrieval, Pattern Recognition Letters, Volume 83, Part 3, 1 November 2016, Pages 357-367, ISSN 0167-8655, http://dx.doi.org/10.1016/j.patrec.2016.05.021.

Posted in blog, publications, science | Tagged , , , , , , , | Leave a comment

A correlation graph approach for unsupervised manifold learning in image retrieval tasks

In this paper, the authors Daniel Pedronette and Ricardo Torres, discuss a novel unsupervised manifold learning algorithm, which aims at imitating the human behavior in judging similarity among images. The proposed algorithm exploits unlabeled contextual information encoded in the dataset manifold through the Correlation Graph for improving the effectiveness of distance/similarity measures. In this sense, the context can be seen as any complementary information about similarity among images, as the set of images in a strongly connected component.

A large set of experiments was conducted for assessing the effectiveness of the proposed approach, considering different descriptors and datasets. The high effectiveness of the manifold learning algorithm is demonstrated by the experimental results obtained in several image retrieval tasks. The effective- ness gains associated with the low computational efforts required represent a significant advantage of the discussed method when compared with existing approaches proposed in the literature.


Daniel Carlos Guimarães Pedronette, Ricardo da S. Torres, A correlation graph approach for unsupervised manifold learning in image retrieval tasks, Neurocomputing, Volume 208, 5 October 2016, Pages 66-79, ISSN 0925-2312, http://dx.doi.org/10.1016/j.neucom.2016.03.081.

Distance correlation analysis for computing the adjacency of the Correlation Graph

Distance correlation analysis for computing the adjacency of the Correlation Graph

Posted in blog, publications, science | Tagged , , , , , , | Leave a comment

Talk: Media Provenance Analytics: Concepts and Applications of Multimedia Phylogeny

Being part of a series of four talks that will be given at NTU Singapore, in this first talk Prof. Anderson Rocha (RECOD) will explore the research field of Multimedia Phylogeny.

Abstract: Currently, multimedia objects can be easily created, stored, (re)-transmitted, and edited for good or bad. In this sense, there has been an increasing interest in finding the structure of temporal evolution within a set of documents and how documents are related to one another overtime. This process, also known in the literature as Multimedia Phylogeny, aims at finding the phylogeny tree(s) that best explains the creation process of a set of related documents (e.g., images/videos) and their ancestry relationships. Solutions to this problem have direct applications in forensics, security, copyright enforcement, news tracking services and other areas. In this talk, we explore solutions for reconstructing the evolutionary tree(s) associated with a set of visual documents, more specifically images and videos. This can be useful for aiding experts to track the source of child pornography image broadcasting or the chain of image and video distribution in time, being extremely useful for complex different media provenance tasks. Finally, we will also discuss how to implement such solutions in large-scale considering millions of documents at the same time.

If you are interested in the talk’s content, the slides are available here.

Date: 15 Feb 2017, Wednesday

Time: 2.00pm – 3.30 pm (Seated by 1.50pm)

Venue: Demo Room, ROSE Lab, Research Techno Plaza (RTP), Level 4, Border X Block, 50 Nanyang Drive, 637553. Singapore

image-uploaded-from-ios

Posted in blog, Keynotes, science, talk | Tagged , , , , , , | Leave a comment

On the Reconstruction of Text Phylogeny Trees: Evaluation and Analysis of Textual Relationships

In this article, recently accepted at PLOS ONE journal and available as open access, the authors propose a framework for reconstructing text evolutionary trees, aiming at reconstructing the history of modifications that a set of related documents has gone through.

A serie of distinct combinations of dissimilarity measures and reconstruction strategies are evaluated with extensive experiments, including a set of artificial near-duplicate documents and documents collected from Wikipedia. Moreover, two potential application areas of the proposed framework are discussed: plagiarism and stemmatology.


Marmerola GD, Oikawa MA, Dias Z, Goldenstein S, Rocha A (2016) On the Reconstruction of Text Phylogeny Trees: Evaluation and Analysis of Textual Relationships. PLOS ONE 11(12): e0167822. doi: 10.1371/journal.pone.0167822

Proposed framework. Given n near-duplicate documents, an n × n symmetric dissimilarity matrix M is calculated. This matrix is used to construct an undirected tree using a minimal spanning tree algorithm, from which we can use an heuristic or other strategies to infer the root and the edges’ directions, obtaining the final configuration of the tree.

Proposed framework. Given n near-duplicate documents, an n × n symmetric dissimilarity matrix M is calculated. This matrix is used to construct an undirected tree using a minimal spanning tree algorithm, from which we can use an heuristic or other strategies to infer the root and the edges’ directions, obtaining the final configuration of the tree.

Posted in blog, publications, science | Tagged , , , , , , , , , , , , | Leave a comment

On Interactive Learning-to-Rank for IR: Overview, Recent Advances, Challenges, and Directions

In this article, the authors deal with the problem of creating interactive information retrieval (IIR) systems nowadays. The work reviews several interactive retrieval related aspects focusing mainly on recent advances, important challenges and promising research directions.
The paper shows that, while the research community achieved important advances in the last decades and specially in the latest years, some important questions still pose great challenges.


Rodrigo Tripodi Calumby, Marcos André Gonçalves, Ricardo da Silva Torres, On interactive learning-to-rank for IR: Overview, recent advances, challenges, and directions, Neurocomputing, Volume 208, 5 October 2016, Pages 3-24, ISSN 0925-2312, http://dx.doi.org/10.1016/j.neucom.2016.03.084.

Conceptual map of the Interactive Information Retrieval field.

Conceptual map of the Interactive Information Retrieval field.

Posted in blog, publications, science | Tagged , , , , , , , , , | Leave a comment

Modeling plant phenology database: Blending near-surface remote phenology with on-the-ground observations

Overview upon data integration and time series extraction from near-surface images and on-the-ground phenological observations

Overview upon data integration and time series extraction from near-surface images and on-the-ground phenological observations

The study of recurrent life cycles events and its relationship to climate, plant phenology, handles multifaceted information that needs to be organized and made promptly accessed by scientific community. In this paper, the authors propose the conceptual design and implementation of a database to store, manage, and manipulate phenological time series and associated ecological information and environmental data.

The database successfully integrates plant based phenological observation, ecological characteristics at individual and species level such as pollination or dispersal syndrome, flower and fruit color, leaf exchange strategy, and many other plants attributes. The model is freely available for download from the e-phenology project home page.

In order to demonstrate its effectiveness, two case studies were conducted. They confirm the expectations about the requirements to the database modeling process and demonstrate the wide potential to solve the e-phenology project questions and any other general query for phenology studies.


Greice C. Mariano, Leonor Patricia C. Morellato, Jurandy Almeida, Bruna Alberton, Maria Gabriela G. de Camargo, Ricardo da S. Torres, Modeling plant phenology database: Blending near-surface remote phenology with on-the-ground observations, Ecological Engineering, Volume 91, June 2016, Pages 396-408, ISSN 0925-8574, http://dx.doi.org/10.1016/j.ecoleng.2016.03.001.

Posted in blog, publications, science | Tagged , , , , , , , , , , , , | Leave a comment

A multimodal query expansion based on genetic programming for visually-oriented e-commerce applications

The article entitled “A multimodal query expansion based on genetic programming for visually-oriented e-commerce applications” presents a novel multimodal query expansion strategy, based on genetic programming (GP), for image search in visually-oriented e-commerce applications. The proposed solution allows finding relevant products related to an image query even though their image representation is not (very) similar to the query.

In order to evaluate the solution, the authors adopted the scenario of searching for fashion and accessories in e-commerce Web sites. The achieved results indicate that expressive gains in the quality of the responses can be obtained in this scenario when using our proposed multimodal expansion method, in comparison to use adhoc solutions or even other learning-to-rank alternatives.


Patrícia C. Saraiva, João M.B. Cavalcanti, Edleno S. de Moura, Marcos A. Gonçalves, Ricardo da S. Torres, A multimodal query expansion based on genetic programming for visually-oriented e-commerce applications, Information Processing & Management, Volume 52, Issue 5, September 2016, Pages 783-800, ISSN 0306-4573, http://dx.doi.org/10.1016/j.ipm.2016.03.001.

Examples of search results for image query (a), where Expanded-GPI (c) obtained better precision scores than Visual-GP (b).

Examples of search results for image query (a), where Expanded-GPI (c), which uses multimodal features, obtained better precision scores than Visual-GP (b), which uses only visual features.

Posted in blog, publications, science | Tagged , , , , , , , , , , | Leave a comment

Pixel-Level Tissue Classification for Ultrasound Images

Pixel Intensity distribution of the tissues

Pixel Intensity distribution of the tissues

This paper presents a new method for classifying tissues in ultrasound imagery at the pixel level. The proposed method is basically composed of 1) image normalization, 2) multiscale description, and 3) classification. The main advantage of the proposed method is its capacity to consider pixel-neighboring patterns, which are not encoded by existing methods based on isolated pixel values.

It was experimentally evaluated in tissue and carotid images. A comparison with the state-of-the-art techniques for pixel-level classification shows the quality of the proposed method and its advantages. A prototype implementing the proposed method is currently in use in the University of Campinas Hospital, Brazil.


D. V. Pazinato, B. V. Stein, W. R. de Almeida, R. O. Werneck, P. R. Mendes Júnior, O. A. B. Penatti, R. S. Torres, F. H. Menezes, A. Rocha. “Pixel-Level Tissue Classification for Ultrasound Images,” in IEEE Journal of Biomedical and Health Informatics, vol. 20, no. 1, pp. 256-267, Jan. 2016. doi: 10.1109/JBHI.2014.2386796

Posted in blog, publications, science | Tagged , , , , , , , , , , , , , , , , | Leave a comment

Combining re-ranking and rank aggregation methods for image retrieval

In this paper, entitled “Combining re-ranking and rank aggregation methods for image retrieval”, the authors Daniel Pedronette and Ricardo Torres propose four novel approaches for combining re-ranking and rank aggregation methods aiming at improving the effectiveness of CBIR systems. They discuss how to combine (i) re-ranking algorithms; (ii) rank aggregation algorithms, and both (iii) re-ranking and rank aggregation algorithms.

The proposed approaches are evaluated considering visual (shape, color, and texture descriptors) and multimodal retrieval (visual and textual descriptors). Experimental results demonstrate that their combination approaches can further improve the effectiveness of image retrieval systems.


Daniel Carlos Pedronette and Ricardo Da Torres. 2016. Combining re-ranking and rank aggregation methods for image retrieval. Multimedia Tools Appl. 75, 15 (August 2016), 9121-9144. DOI: http://dx.doi.org/10.1007/s11042-015-3044-0

Main steps of the Contextual Re-ranking algorithm

Main steps of the Contextual Re-ranking algorithm

Posted in blog, publications, science | Tagged , , , , , , , | Leave a comment