I am working with raw DNG files I have captured with iphone 11 and iphone 12 ( I used Moment app to capture raw - not proraw). I want to check the linearity of raw RGB according to ISO. It is (almost) linear up to ISO of around 200. Apparently there is a Baseline Exposure and also a Exposure Bias (or Exposure Compensation) tag available in the DNG.
I correct the linear values based on 2^(baselineExposure+exposureCompensation) and it still does not fix my linearity issue.
The best fit (very strange) I could get to my data was 2^baselineExposure * 2^(-10*exposureCompensation) but still far from linear.
Anybody knows how to interpret those tags?
Thanks, Hamid
