Stamp detection in scanned documents

The article presents current challenges in stamp detection problem. It is a crucial topic these days since more and more traditional paper documents are being scanned in order to be archived, sent through the net or just printed. Moreover, an electronic version of paper document stored on a hard drive can be taken as forensic evidence of possible crime. The main purpose of the method presented in the paper is to detect, localize and segment stamps (imprints) from the scanned document. The problem is not trivial since there is no such thing like stamp standard. There are many variations in size, shape, complexity and ink color. It should be remembered that the scanned document may be degraded in quality and the stamp can be placed on a relatively complicated background. The algorithm consists of several steps: color segmentation and pixel classification, regular shapes detection, candidates segmentation and verification. The paper includes also the initial results of selected experiments on real documents having different types of stamps

Anveshak - A Groundtruth Generation Tool for Foreground Regions of Document Images

We propose a graphical user interface based groundtruth generation tool in this paper. Here, annotation of an input document image is done based on the foreground pixels. Foreground pixels are grouped together with user interaction to form labeling units. These units are then labeled by the user with the user defined labels. The output produced by the tool is an image with an XML file containing its metadata information. This annotated data can be further used in different applications of document image analysis.Comment: Accepted in DAR 201

Variability of stamp impression measurements under different apposition conditions

When a forensic document examiner obtains differences in size measurements between a questioned and reference stamp impressions, it may be difficult to assess whether such findings might be due to the use of the same stamp in different apposition conditions or are due to the use of different stamps. To address this issue, the present work has studied the variability of size measurements of stamp impressions apposed in various (pressure, humidity and temperature) conditions. Different stamps were also used to evaluate the influence of the fabricant, the matrix (photopolymer or rubber) and the inking type (self-inking and handstamp). While statistical tests sometimes indicated differences in the results, the measurement distributions overlapped for all kind of conditions (same stamps, different stamps), except for the two stamps produced by different manufacturers. Based on the findings of this study, a difference above 0.09 cm would support the hypothesis that two different stamps were used to produce the impressions. However, size differences below 0.09 cm were also encountered for impressions made using different stamps. The maximal size difference was actually measured for two stamps produced by different manufacturers (up to 0.29 cm)

Countering illegal UAV flights : passive DVB radar potentiality

International audienceSince a few years, illegal UAV(Unmanned Aerial Vehicle) flights have been observed in different countries and under various environments[1]. Following these malicious fligths, most of the countries decided to counter such illegal activities asking their main industrial and laboratories to provide an already existing global solution against such UAV activities. However, it seems that up to now, none active system has been validated as the universal ideal solution. This paper will analyse the main system requirements. Then the potential of a passive DVB-T (Digital Video Broadcasting- Terrestrial) component will be illustrated using experimental data for both the detection, identification, location and alert functions:•The expected benefits of such a passive DVB-T solution will be analysed by considering experimental results on multi-rotors UAV as well as on fixed wings UAV.•Furthermore, some limitations of such a passive countering UAV component/system will be outlined.In summary, the passive DVB-T component offers very attractive capabilities for struggling against UAV at ranges up to three kilometres and even more in terms of detection, identification, location and alert.The interest of passive component for struggling against UAV is quite new [2] and it has to be noticed that several papers were dedicated to such an application during the last Passive Coherent Location Meeting in Bonn Wachtberg in 2017[3][4][5]

Spatially resolved texture analysis of Napoleonic War era copper bolts

The spatial resolution achievable by a time-of-flight neutron strain scanner has been harnessed using a new data analysis methodology (NyRTex) to determine, nondestructively, the spatial variation of crystallographic texture in objects of cultural heritage. Previous studies on the crystallographic texture at the centre of three Napoleonic War era copper bolts, which demonstrated the value of this technique in differentiating between the different production processes of the different types of bolts, were extended to four copper bolts from the wrecks of HMS Impregnable (completed 1786), HMS Amethyst (1799), HMS Pomone (1805) and HMS Maeander (1840) along with a cylindrical `segment' of a further incomplete bolt from HMS Pomone. These included bolts with works stamps, allowing comparison with documentary accounts of the manufacturing processes used, and the results demonstrated unequivocally that bolts with a `Westwood and Collins' patent stamp were made using the Collins rather than the Westwood process. In some bolts there was a pronounced variation in texture across the cross section. In some cases this is consistent with what is known of the types of hot and cold working used, but the results from the latest study might also suggest that, even in the mature phase of this technology, some hand finishing was sometimes necessary. This examination of bolts from a wider range of dates is an important step in increasing our understanding of the introduction and evolution of copper fastenings in Royal Navy warships