NGC6992 East Veil nebula

A

Andres.Pozo

Well-known member
Last summer I took 16h of H-alpha and O-III in two tiles for testing the script AlignByCoordinates. For composing the mosaic I have used this workflow:
  • Calibrate, register and integrate the two channels and two tiles (Ha-N, Ha-S, O3-N and O3-S).
  • Remove gradients in the four images using DBE.
  • LinearFit of the images of each channel
  • Solve the images using ImageSolver
  • Align the four images using AlignByCoordinates with the "Mosaic" mode
  • Merge the tiles using GradientMergeMosaic
  • Create a RGB image using PixelMath: R=Ha, G=20%Ha+80%O3, B=O3
  • BackgroundNeutralization and ColorCalibration
  • The rest of the workflow is a quite standard one: noise reduction, stretch, HDRwavelets, SCNR, curves

The result is this:


Direct link to the high resolution image
 
Hi Andres,

Thank you for the demonstration of PixInsight's power of seamlessly merging multiple images into one image. The result speaks for itself - you achieved a great and nicely processed result.

If you don't mind I would suggest a slightly different color mapping, which gives you a bit more 'physically correct' color rendition of this object:

R=Ha, G=O3, B=20%Ha+O3 ( the 20% is the contribution of the blue spectral component of Hbeta). I also would use SCNR only with great caution, because it reduces green and shifts the teal color of OIII towards blue.

Best regards,
Gerhard
 
Thanks Gerhard,

I appreciate your suggestion about the color mapping. In this image I didn't seek 'physically correct' colors but only a visually pleasant image.
You are probably right in that the last SCNR step has been too strong and perhaps I should have kept more of the greens.

Andr?s.
 
the Hb line apparently is kind of a dark teal color @ 486.1nm... so shouldn't you also put some of the Hb into the G channel if you are trying to get to some physical meaning?
 
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