NGC 1499 - California Nebula in L-HaRGB

The California nebula (NGC 1499 or SH2-220) is an emission nebula in the constellation Perseus. Due to its low surface brightness, it's hard to observe visually.

For this image I used all provided channels (compare to the second image, in which I only used the RGB and L channels). After all channels were stacked and aligned in SiriL 1.4.0. I did a denosing on all channels using GraxPert via the build in interface (python script) from the SiriL 1.4.0 GUI. Then the RGB channels were combined and a SPCC color calibration was done. and the individual channels saved a separate files. With the Halpha and R channel and continuum subtraction was done using the automated python script provided from eh community for SiriL 1.4.0. With the continuum subtracted channel a recombination using pixelmath was done in which the continuum subtracted Ha channel was blended into the R and B channel (20 % strength of HaCS into B in relation to the strength used in R channel to accommodate for the Hbeta emission in the blue part of the spectrum).

After this was done the image was processed by removing the gradient with AutoBGE, followed by a Veralux stretch. The obtained image was then transferred to Affinity Photo , stars separated (StarXTerminator) and the starless layer combined with a synthetic luminance channel made from this image and the L channel (starless) from the observation. The luminance channel was tone mapped to emphasize the structure of the nebula. Finally, the stars were re-introduced.

In comparison to the LRGB image (see the other post) you can clear see that the intensity of the reds are significantly stronger and further Halpha areas become visible. Please, note that both images were made using a ultra-WideGammut Monitor (100 % AdobeRGB and 98 % DCI-P3 color coverage), because these two images are intended for a print project. This might lead on a normal monitor that you might not be able to see the details in the highly saturated areas of this image.... but they are there.