Because Ha tends to be dominant in a lot of our narrowband images, and because we often map the Ha to Green, the Green channel can dominate the image. There are various techniques that can bring that back into line.
One technique that sometimes works is just to run SCNR on the image and the result colors are much closer to what you probably want to achieve. Here is an example with the internal part of the Heart Nebula that I recently imaged.
Here is the Heart after a LRGB combine (with no L; SII to red, Ha to green, OIII to blue).
One technique that sometimes works is just to run SCNR on the image and the result colors are much closer to what you probably want to achieve. Here is an example with the internal part of the Heart Nebula that I recently imaged.
Here is the Heart after a LRGB combine (with no L; SII to red, Ha to green, OIII to blue).
Now we do a histogram transformation of it so that the data is no longer linear.
Then we run SCNR to help control the green.
Then we add some curves saturation to bring out the color.
Then we do another curves adjustment, this time to up the contrast.
And then we adjust the black point using a histogram transformation again.
We aren't done yet, but we are well on the way there.
I didn't come up with this technique. I first heard about it here:
www.youtube.com/watch?v=v6GHqYyyHg8
I don't know where he got it, or if he came up with it. What I do doesn't really match exactly what he does. I have adapted it somewhat. But I got the underlying idea of using SCNR for Hubble Palette processing from that video.
The technique doesn't work on every image. But it is certain a worthwhile tool in the toolbox.
I didn't come up with this technique. I first heard about it here:
www.youtube.com/watch?v=v6GHqYyyHg8
I don't know where he got it, or if he came up with it. What I do doesn't really match exactly what he does. I have adapted it somewhat. But I got the underlying idea of using SCNR for Hubble Palette processing from that video.
The technique doesn't work on every image. But it is certain a worthwhile tool in the toolbox.