Using the NBRGBCombination script in Pixinsight

In the past, I combined my narrowband data with LRGB images using a tutorial from LighVortexAstronomy. I tried the previous scripts in Pixinsight but they never really worked for me.

First, I use BackgroundNeutralization, ColorCalibration and SCNR on the RGB image to get the colors right. I also use DynamicBackgroundExtraction on the Ha and OIII images to clean up their background (I didn't do this on the RGB images as they are almost completely filled with stars and dust lanes).

This script has a fairly simple interface:

The first step is to select the RGB image and the narrowband images and press "Apply". The script opens a preview window where it shows the result of the combination:

One of the most useful feature are the two buttons RGB and NBRGB. They allow to flip from pure RGB to Narrowband+RGB picture and back. This makes it very easy to see the impact that the narrowband image(s) have.

See the difference between my RGB image and the combined image with default settings:

Pure RGB Image	Combined Image

The Ha data really brought out the red of the nebula. But unfortunately too much as the dust lanes are now also red. In order to reduce the impact, I increase the Scale setting for the Ha data. The default is 1.20, let's increase it to 3 (and click Apply again):

This is better, but the hue of the dark lanes are still very red. I tried various settings in the script, but could not increase the blue / decrease the red further without destroying the nebula). I decided to address this later with masks and CurvesTransformation.

One big caveat of this script:
IF YOU PRESS CANCEL WHILE IT'S RUNNING, PIXINSIGHT MIGHT COMPLETELY CRASH ON YOU (AND ALL UNSAVED PROGRESS IS LOST)!!! (Happened to me several times)