Reverse Digital Typography

Reverse engineering of typefaces has been an active research area of digital typography. However, past research works are limited to typographic parameters extraction and curve fitting, and no reverse-engineering equivalent of any classical digital typesetting software (e.g. METAFONT compiler, LTEX package) exist to date. Interestingly, the rise of cloud computing has made large scale reverse typesetting of ancient books and artworks a real challenge, as the example of Google Books, which calls for reverse typesetting software. In this research report, we present the design and implementation of Reverse METAFONT compiler for reverse typesetting of rasterscanned fonts. We first give an introduction of reverse digital typography. Second, we report algorithms and techniques for generating METAFONT representations of raster-scanned fonts. Third, we report compression algorithms and techniques to reduce the number of control points in METAFONT representations. Two performance metrics are introduced to evaluate the compression algorithms: normalized control points reduction and global mean-squared-error. Finally, we evaluate the algorithms and techniques using Times New Roman font set. We present 52 reverse-engineered Times New Roman alphabets to give a demonstration. Keyword: Typesetting; reverse digital typography; METAFONT; curve fitting; splines; parametric typographic representations