Use a correct color matrix
The color matrix needs to be obtained from a raw picture of a calibrated color target. Here's how:
The forward matrix doesn't seem to be used by dcraw, so a reverse matrix needs to be found too. Adobe DNG spec (public) describes how those are related.
Word of caution, dcraw as used by ufraw seems to have a weird relationship between the color matrix and white balance. Auto white balance is not affected at all by the color matrix (???).
Big camera in daylight, possibly messed up pixel order (fix with exivtool), target https://en.wikipedia.org/wiki/IT8#IT8.7/2_-_1993_(R2003)_Graphic_technology_-_Color_reflection_target_for_input_scanner_calibration :