row noise calibration

[wangchx67]

Hi, I want to query about the details of row noise calibration. Based on the description of paper, the first step is to extract the mean value of each row from raw data, and then sigma_r if obtained by maximize the log-likelihood. I am curious about which row mean value the maximizing log-likelihood of sigma_r is based on :

1. estimate every sigma_r of every rows and calculate the mean of all sigma_r
2. estimate single sigma_r based on the mean value of every row mean value
3. other