Hi Nicholas - That is a very pretty image of the North America Nebula. For only 8 months you are doing well.
1) I noticed a fixed pattern noise that looked kind of like burlap sack across most of the image. Not sure what caused it. Possibly something in the calibration of the images.
2)
BackgroundNeutralization (BN) is important to balance the background colors of your image to make true background "grayish". This is a necessary step for almost all images. This is done using a small Preview in your image where there is nothing but background (no target nebulosity).
3)
ColorCalibration (CC) is very important, and, normally references the Preview used in BN.
4)
HDRMultiscaleTransform is not always necessary, but, can be helpful to bring out details. The best
Number of layers setting will vary from image to image, but, a setting of 5 or 6 would be more normal. Whether to choose
To lightness and/or
Lightness mask will also depend on the image (experiment).
5)
CurvesTransformation is a stretching tool and is really not related to Flats. It can be used to "sharpen" an image when an S-curve is used (pull the curve down a little at about 1/4 of the horizontal scale and pul the curve up a little at about 3/4 of the horizontal scale) for the
RGB/K setting. When the
S setting is selected, raising the curve will increase the color saturation in your image which can greatly enhance an image.
6)
Deconvolution can be tricky but useful. The link below is to a good tutorial on how to use Deconvolution.
https://www.youtube.com/watch?v=97OyeSR76Fs7) I use
LHE on almost every image I process. I usually apply a Luminance Mask to the image and then use LHE with a
Kernel radius of about 26. I adjust the
Amount to get the desired amount of detail sharpening. I then apply LHE again but this time with a
Kernel radius of about 110. This helps to brighten larger area details in the image. Again I adjust the
Amount to get the desired amount of enhancement.
You are definitely on a good path in your processing. I looked at you nice image on Astrobin.
There are a series of wonderful video tutorials at Harry's Astroshed. Each one is only about 5-10 minutes as I remember, and, only one topic is discussed, so, they are easy to follow, and free! I found them extremely useful when learning PI. Below is a link to the tutorials at Harry's website.
https://www.harrysastroshed.com/pixinsight/pixinsight%20video%20html/Pixinsighthome.htmlHope this helps.
Steve