Sheraz Ahmed

ICDAR 2013 Competitions on Signature Verification and Writer Identification for On- and Offline Skilled Forgeries (SigWiComp 2013)

This paper presents the results of the ICDAR2013 competitions on signature verification and writer identification for on- and offline skilled forgeries jointly organized by PR researchers and Forensic Handwriting Examiners (FHEs). The aim is to bridge the gap between recent technological developments and forensic casework. Two modalities (signatures, and handwritten text) are considered where training and evaluation data (in Dutch and Japanese) were collected and provided by FHEs and PR-researchers. Four tasks were defined where the systems had to perform Dutch offline signature verification, Japanese offline signature verification, Japanese online signature verification, and Dutch writer identification. The participants of the signatures modality were motivated to report their results in Likelihood Ratios (LR). This has made the systems even more interesting for application in forensic casework. For evaluation of signatures modality, we used both the traditional Equal Error Rate (EER) and forensically substantial Cost of Log Likelihood Ratios (Ĉllr). The system having the smallest value of the Minimum Cost of Log Likelihood Ratio (Ĉllrmin) is declared winner. For evaluation of the handwritten text modality, we used the precision and accuracy measures and winners are announced on the basis of best F-measure value.

Improved Automatic Analysis of Architectural Floor Plans

This paper proposes a novel complete system for automated floor plan analysis. Besides applying and improving state-of-the-art processing methods, we introduce novel preprocessing methods, e.g., the differentiation between thick, medium, and thin lines and the removal of components outside the convex hull of the outer walls. Especially the latter method increases the performance of the final system. In our experiments on a reference data set we compare our approach to other approaches available in the literature. We show that our system outperforms previous systems. The final room recognition accuracy is 79 % that is 10 % higher than the 69 % achieved by a state-of-the-art approach from the literature.

Automatic Room Detection and Room Labeling from Architectural Floor Plans

This paper presents an automatic system for analyzing and labeling architectural floor plans. In order to detect the locations of the rooms, the proposed systems extracts both, structural and semantic information from given floor plans. Furthermore, OCR is applied on the text layer to retrieve the meaningful room labeling. Finally, a novel post-processing is proposed to split rooms into several sub-regions if several semantic rooms share the same physical room. Our fully automatic system is evaluated on a publicly available dataset of architectural floor plans. In our experiments, we could clearly outperform other state-of-the-art approaches for room detection.

Text/Graphics Segmentation in Architectural Floor Plans

In this paper, we propose an improved method for text/graphics segmentation. Text/graphics separation is a crucial preprocessing step in document analysis before further analysis and recognition can be applied. Our proposed system extends the method of Tombre et al. with a number of improvements to make it more suitable for architectural floor plans. A crucial novel preprocessing step is the detection and removal of walls before the actual segmentation. Furthermore, text components are then extracted by analyzing connected components and even considering text overlapping with graphics. Finally, a smearing approach is used to remove noise and extract the final text components. Evaluation results over the series of 90 floor plans which has also been used in reference work shows that our method has a recall of almost 99 % and a precision greater then 97%.

Extraction of Text Touching Graphics Using SURF

In this paper we propose a novel part-based method for the extraction of text touching graphic components. The Speeded Up Robust Features (SURF) are used to localize the text components and distinguish them from graphics. We introduce several post-processing steps to finally detect the text. We have tested our method on a publicly available data set of architectural floor plans and on real geographical maps. On floor plans we have located more than 95% of the text components which were not identified as text beforehand because they were touching graphic components.

A Signature Verification Framework for Digital Pen Applications

In this paper we present a framework for real-time online signature verification scenarios. The proposed framework is based on state-of-the-art feature extraction and Gaussian Mixture Model (GMM) classification. While our signature verification library is generally applicable to any input device using digital pens, we have implemented verification scenarios using the Anoto digital pen. As such our automated signature verification framework becomes an interesting commodity for industry, because the Anoto SDK is easy to apply and the GMM-based classification can be seamlessly integrated. The novelty of this work is the application of our framework that takes real-time online signature verification to every scenario where digital pens may potentially be used. In this paper we describe several scenarios where our framework has been applied, including signatures in financial contracts or ordering processes. We also propose a general approach to integrate the GMM-descriptions into electronic ID-cards in order to also store behavioral biometrics on these cards. In experiments we have measured the performance of the signature verification system when skilled forgeries were present. The interest shown by our partner financial institutions and the results of our initial evaluations indicate that our signature verification framework suits exactly the demands of our clients.

Signature Segmentation from Document Images

In this paper we propose a novel method for the extraction of signatures from document images. Instead of using a human defined set of features a part-based feature extraction method is used. In particular, we use the Speeded Up Robust Features (SURF) to distinguish the machine printed text from signatures. Using SURF features makes the approach generally more useful and reliable for different resolution documents. We have evaluated our system on the publicly available Tobacco-800 dataset in order to compare it to previous work. Finally, all signatures were found in the images and less than half of the found signatures are false positives. Therefore, our system can be applied for practical use.

A Generic Method for Stamp Segmentation Using Part-Based Features

Traditionally, stamps are considered as a seal of authenticity for documents. For automatic processing and verification, segmentation of stamps from documents is pivotal. Existing methods for stamp extraction mostly employ color and/or shape based techniques, thereby limiting their applicability to only colored and specific shape stamps. In this paper, a novel, generic method based on part-based features is presented for segmentation of stamps from document images. The proposed method can segment black, colored, unseen, arbitrary shaped, textual, as well as graphical stamps. The proposed method is evaluated on a publicly available dataset for stamp detection and verification and achieved recall and precision of 73% and 83% respectively, for black stamps which were not addressed in the past.

Automatic Ground Truth Generation of Camera Captured Documents Using Document Image Retrieval

In this paper a novel method for automatic ground truth generation of camera captured document images is proposed. Currently, no dataset is available for camera captured documents. It is very difficult to build these datasets manually, as it is very laborious and costly. The proposed method is fully automatic, allowing building the very large scale (i.e., millions of images) labeled camera captured documents dataset, without any human intervention. Evaluation of samples generated by the proposed approach shows that 99.98% of the images are correctly labeled. Novelty of the proposed approach lies in the use of document image retrieval for automatic labeling, especially for camera captured documents, which contain different distortions specific to camera, e.g., blur, occlusion, perspective distortion, etc.

FREAK for Real Time Forensic Signature Verification

This paper presents a novel signature verification system based on local features of signatures. The proposed system uses Fast Retina Key points (FREAK) which represent local features and are inspired by the human visual system, particularly the retina. To locate local points of interest in signatures, two local key point detectors, i.e., Features from Accelerated Segment Test (FAST) and Speeded-up Robust Features (SURF), have been used and their performance comparison in terms of Equal Error Rate (EER) and time is presented. The proposed system has been evaluated on publicly available dataset of forensic signature verification competition, 4NSigComp2010, which contains genuine, forged, and disguised signatures. The proposed system achieved an EER of 30%, which is considerably very low when compared against all the participants of the said competition. In addition to EER, the proposed system requires only 0.6 seconds on average to verify a 3000*1500 scanned signature. This shows that the proposed system has a potential and suitability for forensic signature verification as well as real time applications.