Gerhard Fuernkranz wrote:
If the white readings happen to be < 1000 at particular wavelenghts, then a minimum value of 1000 is still enforced for the denominator, which I assume will lead to a downwards shrinkage/biasing of the readings at these wawevelengths. It should be easy, to print out the write_ref1 and white_ref2 numbers in order to verify whether or not they happen to be < 1000 your case.
Yes, this case is there to avoid low reference readings magnifying noise, or (ultimately) causing a divide by zero or -ve values. Graeme Gill.