Since each row corresponds to a summation surface, I apply the row normalization to imaging operators implemented as (sum) pull operators, and solve the normalized system:
The solution in equ-mod is equivalent to applying the imaging operator followed by a diagonal transformation . Therefore, I refer to this normalization as model or image normalization. Given that each row of corresponds to an output bin, represents a normalization by the coverage after imaging. This coverage is the imaging fold, e.g, AMO fold, DMO fold ... etc.