Institut für Print- und Medientechnik der TU Chemnitz [Institute for Print and Media Technology • Chemnitz University of Technology] Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing Stefan Pletschacher; Marcel Eckert; Arved C. Hübler
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Institut für Print- und Medientechnik der TU Chemnitz [Institute for Print and Media Technology Chemnitz University of Technology] Direktor: Prof. Dr.
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Institut für Print- und Medientechnik der TU Chemnitz[Institute for Print and Media Technology • Chemnitz University of
Technology] Direktor: Prof. Dr. Arved C. Hübler • Reichenhainer Str. 70 • 09126 Chemnitz • Germany
• Polygonal Approximation Based on Relaxation- Phase 1: Clustering of polygonal points- Phase 2: Relaxation (Error correction)
• Automatic Parameter Control- Rasterization of the resulting glyph images- Ascertaining a weighted error (Ground Truth)- Selecting appropriate vectorization parameters
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Finding Connected Components
Ü Ö Ä % “ !
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Region Growing
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Contour Following
white pixel
black pixel
starting point
examination order
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Clustering of Polygonal Points
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Relaxation
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SVG Representation
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Visual Quality
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Formal Quality Measurement - Ground Truth
Error function- absolute number of wrong pixels- weighted by the distance to the next true component
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Results
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0,3
0,4
0,5
0,6
0,7
0,8
0,9
1
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 1,1 1,2
vectorization parameter ε
acc
ura
cy
H K d
Adaptive Parameter Control
-5
-4
-3
-2
-1
0
1
2
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 1,1 1,2
vectorization parameter ε
accu
racy
gra
die
nt
H K d
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Compression rates
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Conclusions
• Good vectorization results already with linear primitives• High compression rates can be achieved• Extracted fonts can be easily scaled and further formatted• Known vectorization methods have been extended towards an adaptive system for automatic parameter control• These methods can be applied for preservation and handling of unknown type faces in digitized documents• Originals may be re-encoded using a document specific alphabet and font• Direct integration into XML/SVG based processes possible• Various output formats can be supported by means of XSL transformations
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