FREETYPE & PATENTS

The TrueType bytecode patents have expired!

Since May 2010, all patents related to bytecode hinting have expired worldwide. It it thus no longer necessary to disable the bytecode interpreter, and starting with FreeType version 2.4, it is enabled by default.

• Patent #1: US5155805: Method and apparatus for moving control points in displaying digital typeface on raster output devices

• Patent #2: US5159668: Method and apparatus for manipulating outlines in improving digital typeface on raster output devices

• Patent #3: US5325479: Method and apparatus for moving control points in displaying digital typeface on raster output devices

Other patent issues

The colour filtering algorithm of Microsoft's ClearType technology for subpixel rendering is covered by patents. Note that subpixel rendering per se is prior art; using a different colour filter thus circumvents Microsoft's patent claims.