70 research outputs found
Analysis of texture and connected-component contours for the automatic identification of writers
Recent advances in "off-line" writer identification allow for new applications in handwritten text retrieval from archives of scanned historical documents. This paper describes new algorithms for forensic or historical writer identification, using the contours of fragmented connected-components in free-style handwriting. The writer is considered to be characterized by a stochastic pattern generator, producing a family of character fragments (fraglets). Using a codebook of such fraglets from an independent training set, the probability distribution of fraglet contours was computed for an independent test set. Results revealed a high sensitivity of the fraglet histogram in identifying individual writers on the basis of a paragraph of text. Large-scale experiments on the optimal size of Kohonen maps of fraglet contours were performed, showing usable classification rates within a non-critical range of Kohonen map dimensions. The proposed automatic approach bridges the gap between image-statistics approaches and purely knowledge-based manual character-based methods
Generalized diagonal crossed products and smash products for quasi-Hopf algebras. Applications
In this paper we introduce generalizations of diagonal crossed products,
two-sided crossed products and two-sided smash products, for a quasi-Hopf
algebra H. The results we obtain may be applied to H^*-Hopf bimodules and
generalized Yetter-Drinfeld modules. The generality of our situation entails
that the "generating matrix" formalism cannot be used, forcing us to use a
different approach. This pays off because as an application we obtain an easy
conceptual proof of an important but very technical result of Hausser and Nill
concerning iterated two-sided crossed products.Comment: 41 pages, no figure
Braided Hopf algebras obtained from coquasitriangular Hopf algebras
Let be a coquasitriangular Hopf algebra, not necessarily finite
dimensional. Following methods of Doi and Takeuchi, which parallel the
constructions of Radford in the case of finite dimensional quasitriangular Hopf
algebras, we define , a sub-Hopf algebra of , the finite dual of
. Using the generalized quantum double construction and the theory of Hopf
algebras with a projection, we associate to a braided Hopf algebra
structure in the category of Yetter-Drinfeld modules over .
Specializing to , we obtain explicit formulas which endow
with a braided Hopf algebra structure within the category of
left Yetter-Drinfeld modules over .Comment: 43 pages, 1 figur
A novel approach for handedness detection from off-line handwriting using fuzzy conceptual reduction
Automatic writer identification using connected-component contours and edge-based features of uppercase western script
In this paper, a new technique for offline writer identification is presented, using connected-component contours (COCOCOs or CO(3)s) in uppercase handwritten samples. In our model, the writer is considered to be characterized by a stochastic pattern generator, producing a family of connected components for the uppercase character set. Using a codebook of CO(3)s from an independent training set of 100 writers, the probability-density function (PDF) of CO(3)s was computed for an independent test set containing 150 unseen writers. Results revealed a high-sensitivity of the CO(3) PDF for identifying individual writers on the basis of a single sentence of uppercase characters. The proposed automatic approach bridges the gap between image-statistics approaches on one end and manually measured allograph features of individual characters on the other end. Combining the CO(3) PDF with an independent edge-based orientation and curvature PDF yielded very high correct identification rates
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