There was a large variety of regularization and optimization techniques used. An embarrassingly large amount of manual work went into both.
In this use the gamma is the inverse of something close to 2.6. Butteraugli needs both gamma correction and inverse gamma correction.
The FFT co-efficients only look weird, but they should actually lead to a symmetric result if our math is correct. In a future version we move away from the FFT, so I don't encourage anyone to actually debug that too much.
