Automatic Generation of Script Font Ligatures Based on Curve Smoothness Optimization

The idea of type as a fixed geometrical object is shown to be inadequate for script types. The method presented creates ligatures between script font glyphs on-the-fly, i.e. as a part of the glyph rasterization process. This is done by manipulation of an existing font. So the process described here can be used to give existing fonts the intelligence to join characters correctly when being interpreted by a standard font rasterizer or print server. Of vital importance to the method is the natural appearance of the curve serving as the ‘ligature backbone’. In this article, a new smoothness criterion for curves is developed. Then, a method is presented that creates a curve connecting two given curves in a natural-looking way — this is done by optimizing a parametric curve by means of the new criterion. With this algorithm being integrated into on-the-fly generation of script font ligatures, these ligatures get the required level of quality.