Implementing emoji and other colored symbols in PDF
We are used to setting text in color, but for decades operating systems and font formats supported only monochrome fonts where the font specifies only the shape of a glyph, but not its color. While you can apply color when using the font, individual glyphs didn't contain their own colors. The rising popularity of emoji characters, people and object icons and myriads of other colorful symbols spurred the development of extensions to the common OpenType font format. Alas, the industry came up with no less than four competing color extensions of the OpenType font format (Adobe/Mozilla SVG, Microsoft COLR, Google CBDT, Apple SBIX), all of which are included in the relevant standard ISO 14496-22. All of these color font flavors describe glyphs with intrinsic color, but unfortunately none of these formats is supported in PDF. So how can we express color fonts in PDF? This presentation provides an overview of OpenType color fonts and their possible representations in PDF. This will give us an opportunity to take a look at the details of PDF font technology, examine subtle Unicode features, and along the way dive into the wonderful world of lesser known yet standardized emoji characters.
Slides download: https://www.pdfa.org/wp-content/uploads/2021/06/OpenType-Color-Fonts-in-PDF.pdf