# Color Spectrum to Log Octave Mapping

The range of human vision is 370THz at the red end of the spectrum to 740Thz at the blue end. This corresponds to exactly one frequency-doubled octave. When we apply the 12-step ET log scale using semitones of 2^(1/12) to this color octave, a 12-step color wheel can be constructed and mapped onto a musical octave.

It is not a random coincidence that our visual spectrum recognizes a frequency-doubled color octave any more than our auditory spectrum recognizes a frequency-double pitch octave. The human brain perceives this without training and so must itself be organized according to frequency doubling, which is the first harmonic overtone in the harmonic series.