Unfortunately, information on the FXAA algorithm is sparse, and much of it
has been lost to time. The original FXAA algorithm was published in a
whitepaper by NVIDIA
and was severely optimized by the author on the suggestions
of many mostly anonymous contributors. The latest published version of
the algorithm (version 3.11) bears little resemblance to the original
and no documentation exists on the changes. The 3.11 version of the
algorithm is constructed from a maze of C preprocessor macros, and
many different variations of the algorithm are possible based on how
the parameter macros are defined.
The implementation of FXAA in the io7m-r1
package is a set of GLSL expansions of the public domain
Fxaa3_11.h header with a few minor modifications
(unused parameter removals). Specifically, the
PC algorithm is used, with quality presets
(10, 15, 20, 25, 29, 39).