Writer Identification of Arabic Handwritten Digits

This paper addresses the identification of Arabic handwritten digits. In addition to digit identifiability, the paper presents digit recognition. The digit image is divided into grids based on the distribution of the black pixels in the image. Several types of features are extracted (viz. gradient, curvature, density, horizontal and vertical run lengths, stroke, and concavity features) from the grid segments. K-Nearest Neighbor and Nearest Mean classifiers are used. A database of 70000 of Arabic handwritten digit samples written by 700 writers is used in the analysis and experimentations. The identifiability of isolated and combined digits are tested. The analysis of the results indicates that Arabic digits 3 (٣), 4 (٤), 8 (٨), and 9 (٩) are more identifiable than other digits while Arabic digit 0 (٠) and 1 (١) are the least identifiable. In addition, the paper shows that combining the writer’s digits increases the discriminability power of Arabic handwritten digits. Combining the features of all digits, K-NN provided the best accuracy in text-independent writer identification with top-1 result of 88.14%, top-5 result of 94.81%, and top-10 results of 96.48%

Unsupervised Adaptation for Synthetic-to-Real Handwritten Word Recognition

Handwritten Text Recognition (HTR) is still a challenging problem because it must deal with two important difficulties: the variability among writing styles, and the scarcity of labelled data. To alleviate such problems, synthetic data generation and data augmentation are typically used to train HTR systems. However, training with such data produces encouraging but still inaccurate transcriptions in real words. In this paper, we propose an unsupervised writer adaptation approach that is able to automatically adjust a generic handwritten word recognizer, fully trained with synthetic fonts, towards a new incoming writer. We have experimentally validated our proposal using five different datasets, covering several challenges (i) the document source: modern and historic samples, which may involve paper degradation problems; (ii) different handwriting styles: single and multiple writer collections; and (iii) language, which involves different character combinations. Across these challenging collections, we show that our system is able to maintain its performance, thus, it provides a practical and generic approach to deal with new document collections without requiring any expensive and tedious manual annotation step.Comment: Accepted to WACV 202

A writer identification and verification system using HMM based recognizers

In this paper, an off-line, text independent system for writer identification and verification of handwritten text lines using Hidden Markov Model (HMM) based recognizers is presented. For each writer, an individual recognizer is built and trained on text lines of that writer. This results in a number of recognizers, each of which is an expert on the handwriting of exactly one writer. In the identification and verification phase, a text line of unknown origin is presented to each of these recognizers and each one returns a transcription that includes the log-likelihood score for the generated output. These scores are sorted and the resulting ranking is used for both identification and verification. Several confidence measures are defined on this ranking. The proposed writer identification and verification system is evaluated using different experimental setup

Transcriptase–Light: A Polymorphic Virus Construction Kit

Many websites use JavaScript to display dynamic and interactive content. Hence, attackers are developing JavaScript–based malware. In this paper, we focus on Transcriptase JavaScript malware. The high–level and dynamic nature of the JavaScript language helps malware writers to create polymorphic and metamorphic malware using obfuscation techniques. These types of malware change their internal structure on each infection, making them difficult to detect with traditional methods. These types of malware can be detected using machine learning methods. This project creates Transcriptase–Light, a new polymorphic construction kit. We perform an experiment with the Transcriptase–Light against a hidden Markov model. Our experiment shows that the HMM based detector failed in detecting Transcriptase–Light. After observing the results, we try to detect malware using the decryption part of Transcriptase–Light. To avoid detection, we generate the polymorphic version of the decryption part