Back to forums

Should I utilize Sii data for Crescent Nebula? If so, what are some good ways.

Processing Narrowband SII Deep Sky NGC6888
3 replies•146 views
Paul Macias avatar
Paul Macias avatar
Hey guys,

Been imaging Crescent Nebula. Originally I started getting Sulfur along with Hydrogen and Oxygen, but looking at the Sulfur, it doesn't look like it's going to add much. I've been trying some custom blends, but none of them look quite as pleasing as standard HOO palette (which is why I suspect HOO is so common for this target). 

Just curious if others would find it worthwhile to add it, and if so, what would be some basic methods to do so? So far I've just been trying different pixel math blends, but nothing seems that great to me. Below is the Sulfur, Hydrogen, and some custom HOO blend with a bit of Sulfur mixed in the red and green channels (I think). 

I do have RGB for the stars, so that shouldn't be a concern here.  Just looking for ideas and thoughts. Thank you in advance!

Helpful Insightful Respectful Engaging
Oscar avatar
Oscar avatar
starless recipe:

do HOO (and stretch)

get the SII, stretch, and colorize it golden/orange

screen SII onto HOO

it should look great if you do everything right

OHH also sometimes looks great, depending on the object and how you tweak the palette
Paul Macias avatar
Paul Macias avatar
How do you colorize a greyscale image?
Oscar avatar
Oscar avatar
different methods

my personal favorite way is to make a blank image with the same dimensions as your greyscale image (and make the value for this blank image anything above 0)

simply type in something like 0.1 in pixelmath, turn on "create new image", and drag the Process onto your grey nebula image; this will make a new image, a blank dark grey image, with the same dimensions as the nebula image, and with a value of 0.1.

then, bring up Channel Combination, and, if you want a yellow image, for example, you put the nebula image in both the Red and Green channels, but use the blank in the Blue channel

this is simple color mixing logic: Red + Green = Yellow. Start the Channel Combination process.

(for getting a golden colored nebula, I recommend creating a yellow image to start with)

so now, open Background neutralization, make a Preview box in the background of your yellow nebula image, and apply the process

now you should be left with a yellow colored nebula with a dark grey background

all that you need to do now is to change the hue - you can do this with photoshop, or just mess with curves and an inverted luminance mask in PI (or many other ways)



This is my way, I'm not sure how many others do it. Most people just use the NBColourMapper script I think. I find that my method gave better results though.