Constraint-Based approach for Automatic Hinting of Digital Typefaces

By Ariel Shamir.


The rasterization process of characters from digital outline fonts to bitmaps on displays must include additional information in the form of hints beside the shape of characters in order to produce high quality bitmaps. Hints describe constraints on sizes and shapes inside characters and across the font that should be preserved during rasterization. We describe a novel, fast and fully automatic method for adding those hints to characters. The method is based on identifying hinting situations inside characters. It includes gathering global font information and linking it to characters, de ning a set of constraints, sorting them, and converting them to hints in any known hinting technology (PostScript, TrueType or other). Our scheme is general enough to be applied on any language and on complex scripts such as Chinese Japanese and Korean. Although still inferior to expert manual hinting, our method produces high quality bitmap result which approach this goal. The method can also be used as a solid base for further hinting re nements done manually.