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Blending in HA data in nebula - continuum subtraction

starfield
in PixInsight
I'm currently working on processing vdB 152.   The field includes a large red band/swoosh (supernova remnant) that I want to highlight with some HA data.   Is the continuum subtraction method a good way to go here?   Or is that something that is better used when adding HA to galaxies (which works great BTW).

Here's what this looks like without the HA on my Astrobin page.  https://astrob.in/ksftm1/C/



Comments

  • BlockHeadBlockHead
    In terms of galaxies, the continuum subtraction is important because of the starlight (the galaxy) that the HII regions are blended with. This isn't an issue with vdB 152. Subtracting the continuum contribution of the sky can help with the contrast...but  I suspect this is entirely unnecessary. Screening in the Ha contribution is easiest method. I need to make a new video on this...but I do demonstrate in Horizons. The basic idea is that you put the Ha information  into both the Luminance (if you have that) and the Red channel. If you just have RGB... then putting the Ha in the red channel (small amount!) will do the trick. The best result is by blending starless data of course... otherwise you will mess up the stars. In addition, the contribution of the Ha should be thresholded... otherwise the background will no longer by neutral. So you need to determine a level of "useful" information (see Stretch Academy and other videos for what I mean by useful).

    -the Blockhead
  • starfield
    Thanks, Adam.   I'll go back and review the Horizon lesson.   --Steve
  • BlockHeadBlockHead
    This is one example:

    -the BLockhead
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