WBGAIN_ONE_FP
assert((from->wb_gain_gr > 0) && (from->wb_gain_gr < 16 * WBGAIN_ONE_FP));
assert((from->wb_gain_r > 0) && (from->wb_gain_r < 16 * WBGAIN_ONE_FP));
assert((from->wb_gain_b > 0) && (from->wb_gain_b < 16 * WBGAIN_ONE_FP));
assert((from->wb_gain_gb > 0) && (from->wb_gain_gb < 16 * WBGAIN_ONE_FP));