Understanding Local Normalization Jargon

[blueridgeDSIA]

Hello I am trying to utilize local normalization in my process flow.  The "no scale component" check box has a hint which says that it is to limit local normalization to correction of additive gradients exclusively.  Does this refer to clouds passing over by chance, which might add a gradient?   

[pfile]

additive gradients usually means 'light pollution gradients'... multiplicative gradients are optical phenomenon (like vignetting) that would otherwise be corrected by flats.

rob

[blueridgeDSIA]

Thanks, I guess I will try out both options.