Dimitris Arabadjis

Identifying the writer of ancient inscriptions and Byzantine codices. A novel approach

In this paper, a novel methodology is presented aiming at the automatic identification of the writer of ancient inscriptions and Byzantine codices. This identification can offer unambiguous dating of these ancient manuscripts. The introduced methodology is also applicable to contours of complexes of letters or any class of similar curves. The method presented here initially estimates the normalized curvature at each pixel of a letter contour. Subsequently, it performs pair-wise comparisons of the curvatures sequences that correspond to two realizations of the same alphabet symbol. Then, it introduces a new Proposition that, on the basis of the previous results, offers a closed solution to the problem of matching two equinumerous digital contours in the Least Squares sense. Next, a criterion is employed quantifying the similarity of two realizations of the same alphabet symbol. Finally, a number of statistical criteria are introduced for the automatic identification of the writer of ancient manuscripts. The introduced method did not employ any reference manuscript neither the number of distinct hands who had written the considered set of manuscripts nor any related information whatsoever; it also performs quite efficiently even if a small number of realizations (less than 6) of certain alphabet symbols appear in a tested document. The only a priori knowledge is the alphabet of the language under consideration. We would like to stress that otherwise the method does not depend at all on the language itself. Namely it does not take into account if the alphabet is Latin, Greek, Etruscan, etc. The methodology and the related, developed information system has been applied to 46 ancient inscriptions of the Classical and Hellenistic era and 23 Byzantine codices, offering 100% accurate results, in the sense that the obtained results are in full agreement with prominent scholars in the field of Archaeology, History and Classical Studies.

New mathematical and algorithmic schemes for pattern classification with application to the identification of writers of important ancient documents

Abstract: In this paper, a novel approach is introduced for classifying curves into proper families, according to their similarity. First, a mathematical quantity we call plane curvature is introduced and a number of propositions are stated and proved. Proper similarity measures of two curves are introduced and a subsequent statistical analysis is applied. First, the efficiency of the curve fitting process has been tested on 2 shapes datasets of reference. Next, the methodology has been applied to the very important problem of classifying 23 Byzantine codices and 46 Ancient inscriptions to their writers, thus achieving correct dating of their content. The inscriptions have been attributed to ten individual hands and the Byzantine codices to four writers.

Image and pattern analysis for the determination of the method of drawing celebrated thera wall-paintings circa 1650 B.C.

In this article, an integrated conjecture about the method of drawing of monumental prehistoric wall-paintings is presented and supported. Specifically, the article deals with paintings that initially decorated the internal walls of the highest floor of a building, called “Xeste 3”, at Akrotiri of the Greek island of Thera circa. 1650 B.C. It is argued that these wall-paintings could had been drawn while the brush was guided by an apparatus, which corresponds to advanced for the era of geometric prototypes with impressive precision. A set of assumptions concerning the actions the artists might have taken in order to create the spiral themes is stated and supported. These assumptions refer to the existence of a draft plan, the sequence of brush strokes, the placement of the brush on the wall, as well as the possible form of the apparatus. These conjectures are evaluated and tested by means of curve fitting and image analysis methods developed by the authors. The results indicate that all drawn contour parts optimally fit along a single prototype linear spiral with fitting error of less than 0.4mm, supporting existence of a very advanced culture for the era of geometric guide. It is statistically rejected that this guide could have the form of a stamp. Moreover, there is strong evidence that the painter might have used a draft plan of the spiral themes to prepare the final drawing and that the linear spiral guide has been used by alternating its placements in order to form the internal and external spiral contour.

Handwriting automatic classification: Application to ancient Greek inscriptions

In this paper a new approach is presented for automatic writer identification. The approach is applied to the identification of the writer of ancient Greek inscriptions that in turn may offer precise and objective dating of the inscriptions content. Such a dating is crucial for the correct history writing. The methodology is based on the idea of creating an ideal representative of each alphabet symbol in each inscription, via proper fitting of all realizations of the specific symbol in this inscription. Next, geometric features for the ideal representative for each alphabet symbol are defined and extracted and corresponding statistical processing follows based on the computation of the mean value and variance of these characteristics. The decision for writer identification is made via pair-wise, feature based comparisons of the ideal representatives of the inscriptions. Each comparison is implemented by means of multiple statistical tests and an introduced maximum likelihood approach. The system was applied to 33 Athenian inscriptions of classical era which were correctly attributed to 8 different hands, namely with 100% success rate.

Automated reconstruction of fragmented objects using their 3D representation - application to important archaeological finds

In this work a new methodology is introduced for the automated reassembling/reconstruction of fragmented objects using their 3D digital representation. The whole process starts by 3D scanning of the available fragments. These are subsequently properly processed and the obtained fragmentspsila 3D images are automatically tested for possible matching, by means of five novel introduced criteria. The first criterion considers the volume of the gap between two properly placed fragments. Two more criteria consider the fragmentspsila overlapping in each possible matching position. Finally, criteria 4, 5 employ principles from calculus of variations to obtain bounds for the area of the contact surfaces and the length of contact curves. The method has been applied with great success both in the reconstruction of an object artificially broken by the authors and, most important, in the virtual reassembling of parts of wall-paintings made before 1100 BC., excavated highly fragmented in Mycenae and Tiryntha, Greece.

A new approach for ancient inscriptions' writer identification

A novel approach is introduced here for identifying the writer of an ancient inscription, via of methods of pattern recognition, image processing and mathematics. Identifying the writer of an ancient inscription is of fundamental importance for Archaeometry and History, since, it is, so far, the only objective method for dating its content. The introduced method consists in a) pairwise matching of all realizations of an alphabet symbol on two inscriptions. This matching is performed so as to compensate for systematic differences in size, orientation and position of the various letters of the documents, b) a new criterion that quantitatively describes the goodness of fit is given, c) the statistical distribution of quantities associated with this criterion, are estimated, d) novel statistical criteria for deciding if two inscriptions are made by the same writer or not, have been developed. The approach has been successfully applied to 32 Classical and Hellenistic inscriptions, flawlessly classifying them into 9 writers.

Finite precision error analysis of Zernike moments computation schemes and a new, efficient, robust recursive algorithm

Abstract Here, a new approach is introduced that tackles the problem of the quantization error generation and accumulation in any algorithm. This approach offers understanding of the actual cause of generation of finite precision error and the exact tracking of the number of erroneous digits accumulated in all quantities of any algorithm. This approach is applied in the study of popular algorithms evaluating Zernike radial polynomials and moments. The actual sources of the finite precision error in these algorithms are identified and the exact amount of the corresponding numerical error is evaluated. It is shown that, as far as Zernike moments are concerned, this error is independent of the content of the image; it instead depends on the nature of the employed algorithm, the shape of the pixels and the image dimensions. Subsequently, a new, fast, recursive algorithm for the computation of the Polar Zernike polynomials and moments is introduced. The proposed algorithm generates particularly small geometric and integration errors, due to the employed shape of the pixels and the associated recursive relations; it also manifests a considerable resistance to finite precision error. Thus, the algorithm may be applied to high dimensions images (e.g. 2048 × 2048 ) and correspondingly large P m a x .

A new approach for the identification of writers of important ancient documents

In this paper, a novel approach is introduced for identifying the writer of a document, with special emphasis to paleography. Towards this direction, a mathematical quantity called plane curvature is introduced and a number of associated propositions are stated. Proper similarity measures of two curves are defined and a subsequent statistical analysis is applied. The efficiency of the method has been, first, tested on a public reference database. The methodology has also been applied to the very important problem of classifying 23 Byzantine codices and 46 Ancient inscriptions to their writers, thus achieving correct dating of their content. The inscriptions have been attributed to ten individual hands and the Byzantine codices to four writers. Prominent epigraphologists and classicists fully agree with the obtained classification.

Information System for Graphological Identification

In this paper an automated information system is presented, that classifies scripts to corresponding writers using graphology. The methodology is based on the idea of creating a representative of each alphabet symbol in each script via proper fitting of all realizations of the specific symbol in it. The decision for writer identification is based on pair-wise comparisons of statistical quantities computed for all representatives. The system was applied to ancient Greek inscriptions of classical era which were correctly attributed to 6 different hands.

Determination of the method of drawing of prehistoric wall-paintings via original methods of pattern recognition and image analysis

In this paper a new general methodology is introduced for the determination of the method of construction of prehistoric wall-paintings. The approach consists of algorithms that perform a)preprocessing of the contours of the figures appearing in the wall-paintings, b)determination of pattern repetitions in the contours of the depicted entities, c)classification of these repeated patterns into proper geometric prototypes, d)curve fitting. By means of this methodology, the authors demonstrated that a number of wall-paintings excavated at Mycenae and in Aegean islands, made before the 13th century B.C., were drawn via the use of guides. These stencils - guides were very precise geometric figures and in particular linear spirals and hyperbolae, thus indicating knowledge of constructing these complicated schemes more than 1000 years before the appearance of Classical Age mathematics.