DGM NPB filter = psuedo-narrowband with DSLR?
Posted: Sun Mar 06, 2016 7:59 pm
I recently decided to mod my Nikon D5100, and try a session on the Flaming Star Nebula and IC405 area using only the Improved DGM NPB filter by Omega Optical. This filter allows through the spectrum lines of Hb (486nm) and both Oiii (495.9nm + 500.7nm) in one passband, and Ha (656.3nm) in a second 10nm-wide passband, with very sharp dropoffs outside of these target ranges. The result image after a typical StarTools process flow (without using the Color module in fact) is actually fairly well color-balanced when using a full spectrum camera.
But I decided to try to take a narrowband approach to processing it to see if any improved could be gained. I separated the RGB channels of the original linear stack into 3 separate grayscale files, R being quite close to pure Ha, and B+G both representing the Hb/Oiii area. I first processed the R channel to my liking, then I blended the G and B channel files together in the Layer module, and processed it to my liking. Next I created a synthetic luminance by blending the R and G+B files together in the Layer module, giving a significant emphasis to the R file. Then I loaded up this luminance file in the LRGB module as L, the R file as red, and the G+B file as blue, leaving channel interpolation on for StarTools to create the green channel. After some tweaking in the Color module, and a final light denoising in Noiseware, this is my result. I was going for an HST palette appearance, so as to bring out the contrast more of the different areas.
I'm liking this result, but I'm curious if anyone has any ideas as to a better route to process this? I've posted the raw stacked fits file here for anyone interested in taking a swing at it:
https://drive.google.com/open?id=0B3nLN ... Hc1VUt1c1E
But I decided to try to take a narrowband approach to processing it to see if any improved could be gained. I separated the RGB channels of the original linear stack into 3 separate grayscale files, R being quite close to pure Ha, and B+G both representing the Hb/Oiii area. I first processed the R channel to my liking, then I blended the G and B channel files together in the Layer module, and processed it to my liking. Next I created a synthetic luminance by blending the R and G+B files together in the Layer module, giving a significant emphasis to the R file. Then I loaded up this luminance file in the LRGB module as L, the R file as red, and the G+B file as blue, leaving channel interpolation on for StarTools to create the green channel. After some tweaking in the Color module, and a final light denoising in Noiseware, this is my result. I was going for an HST palette appearance, so as to bring out the contrast more of the different areas.
I'm liking this result, but I'm curious if anyone has any ideas as to a better route to process this? I've posted the raw stacked fits file here for anyone interested in taking a swing at it:
https://drive.google.com/open?id=0B3nLN ... Hc1VUt1c1E