The imaging setup
The images were registered, stacked and dark frame corrected in lxnstack, a native Linux application. The final image was processed in the Gimp 2.9.
Nicola has now implemented histograms in the software, some of which can be seen in the live preview screenshots below.
Screenshot showing a linear, averaged RGB histogram
Screenshot showing a logarithmic, averaged RGB histogram
The histograms can also show computed luminance, R, G and B channels as well as the RGB channels together.
Final image of M42/43