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Generating copybooks from consistent handwriting styles
Ralph Niels & Louis VuurpijlNijmegen Institute for Cognition and Information
Radboud University NijmegenThe Netherlands
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Overview
Handwriting styles and copybooks Method Results Discussion
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Handwriting styles
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.
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Applications
Handwriting recognition Personalized recognizers
Handwriting synthesis ‘Handwriting fonts’
Forensic writer identification Human experts use the notion of style
K. Franke, 2005
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Method (1)DataData
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Data
Databases: Unipen trainset Unipen devset Plucoll database
Online handwritten characters(pre-segmented)
43 writers
41 writers
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Method (2)Data
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Clustering of prototypes The prototype we used are averaged
shapes of actual handwritten characters
L. Vuurpijl & L. Schomaker, Finding Structure in Diversity, ICDAR 1997.R. Niels, L. Vuurpijl & L. Schomaker, Automatic allograph matching inforensic writer identification, IJPRAI, Feb. 2007.
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Clustering of prototypes
PCj
PCk
PCi
Prototypes
Prototype clusters
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Method (3)Data
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Create membership vectors
Relative frequency of the occurrence of each prototype cluster in a persons handwriting
0
0,1
0,2
0,3
0,4
0,5
0,6
Writer X
PC 1PC 2PC 3PC 4PC 5
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Create membership vectors(example: handwriting X)
PCj
PCk
PCi
Prototypes
Prototype clusters
0.15
0.05
0.05
0.52
0.23
0.2
0.8
1.0
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Create membership vectors(example: handwriting X, Y and Z)
0
0,1
0,2
0,3
0,4
0,5
0,6
X Y Z
Handwriting Z 0.12
0.01
0.22
0.55
0.10
Handwriting X 0.15
0.05
0.05
0.52
0.23
Handwriting Y 0.47
0.41
0.00
0.09
0.03
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Method (4)Data
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Find writing styles Hierarchical clustering of
membership vectors (handwritings)
H Z X E D I A GB B J K Y C FHandwriting
Writingstyles
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Method (5)Data
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PCj
PCk
PCi
H Z X E D I A GB B J K Y C F
Select consistent handwriting styles
Cluster parameters
Cluster parameters
Level selection
Level selection
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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
Select consistent handwriting styles
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Results
Copybooks Preliminary results Visual evaluation by handwriting
experts Meaningful names Well-known broad categories:
cursive, mixed and print
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Results (example handwritings)
Mixed
Cursive
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Results (prototype occurrence)
Mixed
Cursive
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Discussion 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)
H Z X E D I A GB B J K Y C F
Integrate
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Questions?