1st Mono Imaging Session Help Please

The third combination is actually rather beautiful. Welcome to the world of narrowband! I can't advise as I don't use PI but I do know, this was and still is a challenge for me. You might try balancing the RGB plates using pixel math as this will give you extremely precise control over color balance.

Ryan Génier:
So a few things to remember with mono:

1. There's not really a 'wrong' way to do it. That's the fun of mono, you can experiment with different colour palettes and combinations to see what you like and what works with your data that you've captured.

2. Ha tends to be MUCH stronger than either Sii or Oiii. This is why you tend to end up with colour casts, it all depends on where you assign Ha. In a typical SHO colour palette, you'll end up with a VERY strong green cast because Ha is being assigned to the green channel. It's completely swamping everything else. But there are ways to adjust this.

a. Do a colour calibration AFTER combining which will help to neutralize the green and balance the colours

b. SCNR to completely wipe the green out (which will leave you with your typical gold/blue or

c. (my preference) create a green mask, then adjust the a channel in curves to bring the green balance towards red.

3. One last note - If you're combining your channels in a linear state, you should use Channel Combination. LRGB is a non-linear process, it should really only be used in non-linear (for example combining a luminance image with your RGB image).

Great start, good luck!

Ryan Génier:

Vinny Vent:
Thanks Ryan! I appreciate the detailed response. Super helpful. I’m pretty much of clear understanding on all your points with exception to bullet 2, sub bullet A. If you don’t mind can you explain that a bit more? Sorry if it’s a pain

So when you combine your mono images into a colour image (using whatever palette you prefer), the balance between the channels may not be perfect (some channels may be brighter than others). 

For broadband (RGB) images, the typical advice w/ Pixinsight is to run SPCC to get the colours right. This adjusts the balance of each channel to ensure that the star colours match up w/ known spectra (this is also why you need to plate solve your image before you run SPCC).

But w/ mono, there's not really a 'correct' colour. So how do you balance the colour channels? Well there's a couple of different ways you can do it:

1. Do it all manually - you can use colour masks and luminance masks to adjust each part of the image how you like. This can be a bit tedious, but it works well.

2. If you run the colour calibration process on your combined image (I just use the default settings, but you can play around w/ the background detection and structure detection settings how you like), it will help to balance the colours. This usually results in the green being pulled back slightly (especially where it's overlapping the Oiii). You'll still need to manually adjust the green, but I find this helps automate the process a bit.