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Publications

Publications by José Costa Pereira

2018

Elastic deformations for data augmentation in breast cancer mass detection

Authors
Castro, E; Cardoso, JS; Pereira, JC;

Publication
2018 IEEE EMBS International Conference on Biomedical & Health Informatics, BHI 2018, Las Vegas, NV, USA, March 4-7, 2018

Abstract
Two limitations hamper performance of deep architectures for classification and/or detection in medical imaging: (i) the small amount of available data, and (ii) the class imbalance scenario. While millions of labeled images are available today to build classification tools for natural scenes, the amount of available annotated data for automatic breast cancer screening is limited to a few thousand images, at best. We address these limitations with a method for data augmentation, based on the introduction of random elastic deformations on images of mammograms. We validate this method on three publicly available datasets. Our proposed Convolutional Neural Network (CNN) archi-tecture is trained for mass classification - in a conventional way - , and then used in the more interesting problem of mass detection in full mammograms by transforming the CNN into a Fully Convolutional Network (FCN). © 2018 IEEE.

2011

Maximum Covariance Unfolding : Manifold Learning for Bimodal Data

Authors
Mahadevan, Vijay; Wong, ChiWah; Pereira, JoseCosta; Liu, Tom; Vasconcelos, Nuno; Saul, LawrenceK.;

Publication
Advances in Neural Information Processing Systems 24: 25th Annual Conference on Neural Information Processing Systems 2011. Proceedings of a meeting held 12-14 December 2011, Granada, Spain.

Abstract

2012

On the regularization of image semantics by modal expansion

Authors
Pereira, JoseCosta; Vasconcelos, Nuno;

Publication
2012 IEEE Conference on Computer Vision and Pattern Recognition, Providence, RI, USA, June 16-21, 2012

Abstract
Recent research efforts in semantic representations and context modeling are based on the principle of task expansion: that vision problems such as object recognition, scene classification, or retrieval (RCR) cannot be solved in isolation. The extended principle of modality expansion (that RCR problems cannot be solved from visual information alone) is investigated in this work. A semantic image labeling system is augmented with text. Pairs of images and text are mapped to a semantic space, and the text features used to regularize their image counterparts. This is done with a new cross-modal regularizer, which learns the mapping of the image features that maximizes their average similarity to those derived from text. The proposed regularizer is class-sensitive, combining a set of class-specific denoising transformations and nearest neighbor interpolation of text-based class assignments. Regularization of a state-of-the-art approach to image retrieval is then shown to produce substantial gains in retrieval accuracy, outperforming recent image retrieval approaches. © 2012 IEEE.

2010

A new approach to cross-modal multimedia retrieval

Authors
Rasiwasia, Nikhil; Pereira, JoseCosta; Coviello, Emanuele; Doyle, Gabriel; Lanckriet, GertR.G.; Levy, Roger; Vasconcelos, Nuno;

Publication
Proceedings of the 18th International Conference on Multimedia 2010, Firenze, Italy, October 25-29, 2010

Abstract
The problem of joint modeling the text and image components of multimedia documents is studied. The text component is represented as a sample from a hidden topic model, learned with latent Dirichlet allocation, and images are represented as bags of visual (SIFT) features. Two hypotheses are investigated: that 1) there is a benefit to explicitly modeling correlations between the two components, and 2) this modeling is more effective in feature spaces with higher levels of abstraction. Correlations between the two components are learned with canonical correlation analysis. Abstraction is achieved by representing text and images at a more general, semantic level. The two hypotheses are studied in the context of the task of cross-modal document retrieval. This includes retrieving the text that most closely matches a query image, or retrieving the images that most closely match a query text. It is shown that accounting for cross-modal correlations and semantic abstraction both improve retrieval accuracy. The cross-modal model is also shown to outperform state-of-the-art image retrieval systems on a unimodal retrieval task. © 2010 ACM.

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