Renato Villán

Multilevel 2-D Bar Codes: Toward High-Capacity Storage Modules for Multimedia Security and Management

In this paper, we deal with the design of high-rate multilevel 2-D bar codes for the print-and-scan channel. First, we introduce a framework for evaluating the performance limits of these codes by studying an intersymbol-interference (ISI)-free, synchronous, and noiseless print-and-scan channel, where the input and output alphabets are finite and the printer device uses halftoning to simulate multiple gray levels. Second, we present a new model for the print-and-scan channel specifically adapted to the problem of communications via multilevel 2-D bar codes. This model, inspired by our experimental work, assumes perfect synchronization and absence of ISI, but independence between the channel input and the noise is not assumed. We adapt the theory of multilevel coding with multistage decoding (MLC/MSD) to the print-and-scan channel. Finally, we present experimental results confirming the utility of our channel model, and showing that multilevel 2-D bar codes using MLC/MSD can reliably achieve the high-capacity storage requirements of many multimedia security and management applications

Multilevel 2D bar codes: toward high-capacity storage modules for multimedia security and management

In this paper, we deal with the design of high-rate multilevel 2-D bar codes for the print-and-scan channel. First, we introduce a framework for evaluating the performance limits of these codes by studying an intersymbol-interference (ISI)-free, synchronous, and noiseless print-and-scan channel, where the input and output alphabets are finite and the printer device uses halftoning to simulate multiple gray levels. Second, we present a new model for the print-and-scan channel specifically adapted to the problem of communications via multilevel 2-D bar codes. This model, inspired by our experimental work, assumes perfect synchronization and absence of ISI, but independence between the channel input and the noise is not assumed. We adapt the theory of multilevel coding with multistage decoding (MLC/MSD) to the print-and-scan channel. Finally, we present experimental results confirming the utility of our channel model, and showing that multilevel 2-D bar codes using MLC/MSD can reliably achieve the high-capacity storage requirements of many multimedia security and management applications

Secure surface identification codes

This paper introduces an identification framework for random microstructures of material surfaces. These microstructures represent a kind of unique fingerprints that can be used to track and trace an item as well as for anti-counterfeiting. We first consider the architecture for mobile phone-based item identification and then introduce a practical identification algorithm enabling fast searching in large databases. The proposed algorithm is based on reference list decoding. The link to digital communications and robust perceptual hashing is shown. We consider a practical construction of reference list decoding, which comprizes computational complexity, security, memory storage and performance requirements. The efficiency of the proposed algorithm is demonstrated on experimental data obtained from natural paper surfaces.

Error exponent analysis of person identification based on fusion of dependent/independent modalities: multiple hypothesis testing case

In this paper we analyze the performance limits of multimodal biometric identification systems in the multiple hypothesis testing formulation. For the sake of tractability, we approximate the performance of the actual system by a set of pairwise binary tests. We point out that the attainable error exponent that can be achieved for such an approximation is limited by the worst pairwise Chernoff distance between alternative hypothesis prior models. We consider impact of the inter-modal dependencies on the attainable performance measure and demonstrate that, contrarily to the binary multimodal hypothesis testing framework, an expected performance gain from fusion of independent modalities does not any more play the role of lower bound on the gain one can expect from multimodal fusion.

Authentication of biometric identification documents via mobile devices

We consider the problem of authentication of biometric identification documents via mobile devices such as mobile phones or personal digital assistants (PDAs). We assume that the biometric identification document holds biometric data (e.g., face or fingerprint) in the form of an image and personal data in the form of text, both being printed directly onto the identification document. The proposed solution makes use of digital data hiding in order to crossstore the biometric data inside the personal data and vice versa. Moreover, a theoretical framework is presented that should enable analysis and guide the design of future authentication systems based on this approach. In particular, we advocate the separation approach, which uses robust visual hashing techniques in order to match the information rates of biometric and personal data to the rates offered by current image and text data hiding technologies. We also describe practical schemes for robust visual hashing and digital data hiding that can be used as building blocks for the proposed authentication system. The obtained experimental results show that the proposed system constitutes a viable and practical solution.