The latest AMD Catalyst drivers come with a Catalyst A.I. option which spurred controversy among hardware enthusiasts who considered it an acceptable cheat due to its effect on image quality.
The Catalyst A.I. interface includes an option to change "Texture Filtering Quality" to "High Quality", "Quality", or "Performance", with "Quality being the default setting.
The "High Quality" setting doesn't utilize any optimization and produces uncompromised image quality which reflects the designers' intentions faithfully; the other two settings however introduce varying levels of optimization and introduce little artifacts and changes to the produced images.
AMD's decision to make "Quality" the default setting even though it utilizes optimizations that affect the produced images is what spurred the controversy. Most 3D enthusiasts believe that the default driver settings should produce unaltered images, but AMD seems to believe that the optimizations introduced at that optimization level introduce no visible changes to the produced images.
Guru3D and 3DCenter have tested the optimizations and artifacts introduced by the "Quality" setting and noted that "in environments with a lot of depth, say a road with a textured grid at the end of that road you would be able to spot some anomalies, but only if you look really carefully and with the scene properly lit."
Guru3D has recorded a 3 to 5 fps increase in Dirt 2 and Far Cry 2 when run at "Quality" level instead of "High Quality."