Ralph Niels & Louis Vuurpijl Nijmegen Institute for Cognition and Information Radboud University Nijmegen The Netherlands

 Handwriting styles and copybooks  Method  Results  Discussion

 Handwriting is individual  Similar handwritings: handwriting styles  Top down ‘copybooks’ *  We defined writing styles bottom up * S.-H. Cha, S. Yoon, C.C. Tappert, 2006.

 Handwriting recognition  Personalized recognizers  Handwriting synthesis  ‘Handwriting fonts’  Forensic writer identification  Human experts use the notion of style

 Databases:  Unipen trainset  Unipen devset  Plucoll database  Online handwritten characters (pre-segmented) 43 writers 41 writers

 The prototype we used are averaged shapes of actual handwritten characters L. Vuurpijl & L. Schomaker, Finding Structure in Diversity, ICDAR R. Niels, L. Vuurpijl & L. Schomaker, Automatic allograph matching in forensic writer identification, IJPRAI, Feb

PC j PC k PC i Prototypes Prototype clusters

 Relative frequency of the occurrence of each prototype cluster in a persons handwriting

PC j PC k PC i Prototypes Prototype clusters

Handwriting Z Handwriting X Handwriting Y

 Hierarchical clustering of membership vectors (handwritings) HZXEDIAGBBJKYCF Handwriting Writing styles

PC j PC k PC i HZXEDIAGBBJKYCF

 Monte Carlo simulation of combinations of parameters and levels  Large number of writing styles  Find the writing styles that occur most  By prototypes or  By writers

 Copybooks  Preliminary results  Visual evaluation by handwriting experts  Meaningful names  Well-known broad categories: cursive, mixed and print

Mixed Cursive Print

Mixed Cursive Print

 Applied to/with, not limited to:  Online Latin characters  Dynamic Time Warping for character comparison (human congruous)  Best of both worlds: Integrate top down and bottom up (with forensic experts) HZXEDIAGBBJKYCF Integrate