Santanu Chaudhury

Signature verification using multiple neural classifiers

This paper is concerned with signature verification. Three different types of global features have been used for the classification of signatures. Feed-forward neural net based classifiers have been used. The features used for the classification are projection moments and upper and lower envelope based characteristics. Output of the three classifiers is combined using a connectionist scheme. Combination of these feature based classifiers for signature verification is the unique feature of this work. Experimental results show that combination of the classifiers increases reliability of the recognition results.

Recognition of dynamic hand gestures

This paper is concerned with the problem of recognition of dynamic hand gestures. We have considered gestures which are sequences of distinct hand poses. In these gestures hand poses can undergo motion and discrete changes. However, continuous deformations of the hand shapes are not permitted. We have developed a recognition engine which can reliably recognize these gestures despite individual variations. The engine also has the ability to detect start and end of gesture sequences in an automated fashion. The recognition strategy uses a combination of static shape recognition (performed using contour discriminant analysis), Kalman filter based hand tracking and a HMM based temporal characterization scheme. The system is fairly robust to background clutter and uses skin color for static shape recognition and tracking. A real time implementation on standard hardware is developed. Experimental results establish the effectiveness of the approach.

Devnagari numeral recognition by combining decision of multiple connectionist classifiers

This paper is concerned with recognition of handwritten Devnagari numerals. The basic objective of the present work is to provide an efficient and reliable technique for recognition of handwritten numerals. Three different types of features have been used for classification of numerals. A multi-classifier connectionist architecture has been proposed for increasing reliability of the recognition results. Experimental results show that the technique is effective and reliable.

Text Extraction and Document Image Segmentation Using Matched Wavelets and MRF Model

In this paper, we have proposed a novel scheme for the extraction of textual areas of an image using globally matched wavelet filters. A clustering-based technique has been devised for estimating globally matched wavelet filters using a collection of groundtruth images. We have extended our text extraction scheme for the segmentation of document images into text, background, and picture components (which include graphics and continuous tone images). Multiple, two-class Fisher classifiers have been used for this purpose. We also exploit contextual information by using a Markov random field formulation-based pixel labeling scheme for refinement of the segmentation results. Experimental results have established effectiveness of our approach.

Active recognition through next view planning: a survey

Abstract 3-D object recognition involves using image-computable features to identify 3-D object. A single view of a 3-D object may not contain sufficient features to recognize it unambiguously. One needs to plan different views around the given object in order to recognize it. Such a task involves an active sensor—one whose parameters (external and/or internal) can be changed in a purposive manner. In this paper, we review two important applications of an active sensor. We first survey important approaches to active 3-D object recognition. Next, we review existing approaches towards another important application of an active sensor namely, that of scene analysis and interpretation.

Bengali alpha-numeric character recognition using curvature features

Abstract This paper is concerned with recognition of hand-written and/or printed multifont alpha-numeric Bengali characters. It is assumed that characters are present in an isolated fashion. In the present work characters have been represented in terms of the primitives and structural constraints between the primitives imposed by the junctions present in the characters. The primitives have been characterized on the basis of the significant curvature events like curvature maxima, curvature minima and inflexion points observed along their extent. Curvature properties have been extracted after thinning the smoothed character images and filtering the thinned images using a Gaussian kernel. The unknown samples are classified using a two-stage feed forward neural net based recognition scheme. Experimental results have established the effectiveness of the technique

Biometrics based Asymmetric Cryptosystem Design Using Modified Fuzzy Vault Scheme

We propose a novel biometrics cryptosystem where one can send and receive secure information using just the fingerprints. This cryptosystem is a judicious blend of the asymmetric cryptosystem like RSA and the symmetric fuzzy vault scheme having the advantages of both the aforementioned crypto systems. We have proposed a modification of the fuzzy vault scheme to make it more robust against variations in the values of biometric features. Finally, we propose the use of invariant features as a key to producing a hierarchical security system where the same key (fingerprint) can be used to generate encrypted messages at different levels of security

Trainable script identification strategies for Indian languages

Identification of the script in an image of a document page is of primary importance for a system processing multi-lingual documents. In this paper three trainable classification schemes have been proposed for identification of Indian scripts. The first scheme is based upon a frequency domain representation of the horizontal profile of the textual blocks. The other two schemes use connected components extracted from the textual region. We have proposed a novel Gabor filter-based feature extraction scheme for the connected components. We have also found that frequency distribution of the width-to-height ratio of the connected components can also be used for script recognition. It has been experimentally found that the Gabor filter-based scheme provides the most reliable performance. However, the other two techniques are computationally more efficient.

Matching structural shape descriptions using genetic algorithms

Abstract This paper presents a genetic algorithm for solving the problem of structural shape matching. Both sequential and parallel versions of the algorithm have been presented. The genetic operators-reproduction, crossover and mutation-have been constructed for this specific problem. A new variation of the crossover operator, called the color crossover, is presented. This operator has resulted in significant improvement in runtime and algorithm efficiency. Parallelization has been achieved using an “island” model, with several subpopulations and occasional migration. A complete framework for an object recognition system using this genetic algorithm has been presented. Encouraging experimental results have been obtained.

On adaptive trajectory tracking of a robot manipulator using inversion of its neural emulator

This paper is concerned with the design of a neuro-adaptive trajectory tracking controller. The paper presents a new control scheme based on inversion of a feedforward neural model of a robot arm. The proposed control scheme requires two modules. The first module consists of an appropriate feedforward neural model of forward dynamics of the robot arm that continuously accounts for the changes in the robot dynamics. The second module implements an efficient network inversion algorithm that computes the control action by inverting the neural model. In this paper, a new extended Kalman filter (EKF) based network inversion scheme is proposed. The scheme is evaluated through comparison with two other schemes of network inversion: gradient search in input space and Lyapunov function approach. Using these three inversion schemes the proposed controller was implemented for trajectory tracking control of a two-link manipulator. Simulation results in all cases confirm the efficacy of control input prediction using network inversion. Comparison of the inversion algorithms in terms of tracking accuracy showed the superior performance of the EKF based inversion scheme over others.