1. Stefan Pletschacher; Marcel Eckert; Arved C. Hübler
Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing
Stefan Pletschacher; Marcel Eckert; Arved C. Hübler

2. Digitization of Historical Documents
GEB1150
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

3. Alphabet und Font Extraction
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

4. Vectorization - Raster to Vector Conversion
41 hex
encoded text e.g. ASCII
font assignment
OCR
RIP
bitmap graphic
vector font
Vectorization
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

5. DIA System und Workflow
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

6. DIA System und Workflow
&#xE000
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

7. DIA System und Workflow
XML
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

8. Vectorization Approaches
Contour based
Skeleton based
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

9. Applied Algorithms Pre-processing
- Finding connected components (Region Growing)
- Contour extraction (Contour following)
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
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

10. Finding Connected Components
Ü Ö Ä % “ !
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

11. Region Growing
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

12. Contour Following white pixel black pixel starting point
examination order
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

13. Clustering of Polygonal Points
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

14. Relaxation
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

15. SVG Representation
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

16. Visual Quality
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

17. Formal Quality Measurement - Ground Truth
Error function
- absolute number of wrong pixels
- weighted by the distance to the next true component
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

18. Results
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

19. Adaptive Parameter Control
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

20. Compression rates
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

21. 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
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

22. Thank you very much! Questions stefan.pletschacher@mb.tu-chemnitz.de
Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006