As I look at the data on their web page and also reading the paper they reference ("
https://nae-lab.org/~rei/research/cs/zhao/files/MIRU09.pdf") As I look closer at their web page I believe you are right. I don't think they are reporting the data directly. I don't know about the curve normalization issue you raise when you mentioned multipliers, but it looks like they might be fitting their data to basis sets derived from singular value decompositions. There is not enough information to state this for sure, but if it is true then their data might have some errors relative to the data acquired directly from the cameras. For example, their reported curves are might be a little smoother than the underlying data and may miss some of the small features in the data, e.g. they might not correctly represent the data in the tails of the curves or some small bumps and wiggles in the curves.