Using AutoLinearFit you can do a rough color calibration for dual narrowband images. In fact this script does the following steps: 

If you are using  this workflow then AutoLinearFit can do all these manual steps for you automatically, including selecting the reference image using statistics information.

Just select the RGB image you want to process, select the reference image you prefer (in most cases „Lowest mean“ should be fine) and press OK to run LinearFit on the three color channels. 

< PixInsight Toolbox

Copyright 2021 by Jürgen Terpe