“Model-based matching and hinting of fonts” by Hersch and Betrisey

In today’s digital computers, phototypesetters and printers, typographic fonts are mainly given by their outline descriptions. Outline descriptions alone do not provide any information about character parts like stems serifs, shoulders, and bowls. But, in order to produce the best looking characters at a given size on a specific printer, non-linear operations must be applied to parts of the character shape. At low-resolution, grid-fitting of character outlines is required for generating nice and regular raster characters. For this reason, grid-fitting rules called hints are added to the character description. Grid-fitting rules require as parameters certain characteristic points within the shape outlines. In order to be able to detect these characteristic points in any given input font, a topological model representing the essence of the shapes found in typographic latin typefaces is proposed. This model includes sufficient information for matching existing non-fancy outline fonts to the model description. For automatic hint generation, a table of applicable hints is added into the topological model description. After matching a given input shape to the model, hints which can be applied to the shape of the given font are taken and added to its outline description. Furthermore, a structural description of individual letter shape parts using characteristic model points can be added to the model. Such a description provides knowledge about typographic structure elements like stems, serifs and bowls.

1. D. Adams, “abcdefg: a better constraint driven environment for font generation”, in Andre, Hersch (eds.), Raster Imaging and Digital Typography, Cambridge University Press, 1989. 54-70
2. Apple Computer, TrueType Spec- The TrueType Font Format Specification, July ! 990
3. S. Andler, “Automatic Generation of Gridfitting Hints for Rasterization of Outline Fonts or Graphics”, EPgO- Proceedings of the International Conferen~’e on Electronic Publishing, Document Manipulation & Typography, September 90, (R. Furuta, Ed.) Cambridge University Press, 221-234
4. Berthold Types, H. Berthold AG, Berlin, 1988
5. C. Betrisey, R.D. Hersch, “Flexible Application of Outline Grid Constraints”. in Andre, Hersch (eds.), Raster Imaging and Digital Typography, Cambridge University Press, 1989, 242-250
6. P. Coueignoux, “Character Generation by Computer”, Computer Graphics and Image Processing, Vol. 16, 1981, pp 240- 269.
7. M. Eden, “Handwriting and pattern recognition”. IRE Trans. Inform. Theory, Vol IT-8, 1962, pp 160-166.
8. H.E Feng, T. Pavlidis, “Decomposition of polygons into simpler components: Feature generation for syntactic pattern recognition”, IEEE Transactions on Comp,ters, Vol C-24, June 1975, pp 636-650.
9. J. Flowers, “Digital type manufacture: an interactive approach”, IEEE Computer, May 1984, pp. 40-48.
10. P. Gaskell, “A Nomenclature for the Letterforms of Roman Type”, Vixible Language, Vol 10, No 1.1976.4 I-51.
11. R.D. Hersch, “Character Generation under Grid Constraints”, Proceedings SIGGRAPH’87, ACM Computer Graphics, Vol 21, No. 4, July 1987,243-252
12. P. Karow, Digital Formats for Typefaces, URW Verlag, Hamburg, 1987.
13. D. Knuth, Computer Modern Typefaces, Addison-Wesley, 1986.
14. R. Rubinstein,Digital Typography, An Introduc;ion to Type and Composition for Computer System Design, Addison-Wesley, 1988.
15. L.G. Shapiro, “A Structural Model of Shape”, IEEE PAMI, Vol PAMI-2, No 2, March 1980, pp 111-126.
16. W. Tracy, “Letters of Credit, a view of type design”, Gordon Fraser, London, 1986, pp 52-55.