Dataset: how was the exposure time determined

[hcwang95]

In SID dataset, for a particular scene there are majority of images which were taken using one exposure time. A minority of images are using different exposure times. Also the exposure time of the majority images vary among different scenes (1/30s or 0.04s or 0.1s).

Would you mind sharing how to determine the exposure time based on the scene when you prepare the SID dataset? Thanks a lot!