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Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing

Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing. Stefan Pletschacher; Marcel Eckert; Arved C. Hübler. GEB1150. Digitization of Historical Documents. Alphabet und Font Extraction. Vectorization - Raster to Vector Conversion. 41 hex. encoded text e.g. ASCII.

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Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing

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

  2. GEB1150 Digitization of Historical Documents Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006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. &#xE000 DIA System und Workflow Pletschacher • Vectorization of Glyphs and Their Representation in SVG for XML‑based Processing • ELPUB 2006

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

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