1/0.418985 == 2.38672/1.0 (G/R coeffs ratio). Or, in other words, dcraw_process scales WB coeffs to get full data range after WB applied (and scaled at some time).
BTW, I still not sure that RAW value inversion leads in the right direction. Why not invert (w/ mask subtraction) image after raw processing applied?
1/0.418985 == 2.38672/1.0 (G/R coeffs ratio). Or, in other words, dcraw_process scales WB coeffs to get full data range after WB applied (and scaled at some time).
BTW, I still not sure that RAW value inversion leads in the right direction. Why not invert (w/ mask subtraction) image after raw processing applied?