Automated synthesis of ligatures for arbitrary fonts

Abstract

In typography, ligatures represent a sequence of letters which are connected together to make text more aesthetically pleasing. When creating a new font, typography sometimes do not design certain ligatures. The aim of this project is to study automatic and semi-automatic ways of generating ligatures between common letter pairs and triples to enrich existing fonts which do not have such ligatures. The automatically generated ligatures can be used directly or they can be refined upon by a typographer, reducing the effort required in producing a complete font. In this project we created a system that when given a font with missing ligature characters, it automatically generates the missing ligatures and inserts them into the font. We studied several ligatures from different fonts to extract the parameters of each ligature and we then implemented heuristics to automatically generate ligatures. The system also has a tool which allows users to insert parameters to specify how a ligature is created, in case they would have a certain preference as to how a particular ligature should be generated. After conducting a survey and gathering feedback from domain experts, the synthesized ligatures were found to be aesthetically pleasing as well as readable and legible. Overall the synthesized ligatures were similar to the original ligatures. This being said, there where instances when the synthesized ligatures were slightly different from the original ones, however they were still preferred by the people who participated in the survey. The evaluation also showed that the tool we created to insert parameters, provided the necessary features to create ligatures semi-automatically and could be enhanced further by some minor tweaking, in future works.