Original Introduction
hqx ("hq" stands for "high quality" and "x" stands for magnification) is one of the pixel art scaling algorithms developed by Maxim Stepin, used in emulators such as Nestopia, bsnes, ZSNES, Snes9x, FCE Ultra and many more. There are 3 hqx filters: hq2x, hq3x, and hq4x, which magnify by factor of 2, 3, and 4 respectively.
Port Introduction
hqx-java is a Java port of the excellent hqxSharp C# port, which itself is a port of the original hqx C project
Like the hqxSharp project, the focus of this code is asset creation and usage in tools, so no optimizations were done, just an almost-direct copy of the code.
Usage
Look in the wiki for usage information