How to pull red channel (Ha) from one image and blend it into another RGB image.

[Rudy Pohl]

Hi there,

I have just received as a gift a full spectrum modified Canon T3i camera with a clip-in UV/IR filter, and I have been using an unmodified Nikon D5500 camera for astrophotography for two years. I would like to produce an HaRGB image of the Orion and Running Man Nebula in the surrounding dust as well as other HaRGB images.

I have been advised to pull the Ha (red channel I presume) from the T3i and blend it into the RGB image from the D5500.  The problem is that even though I have quite a bit of experience in Photoshop and Pixinsight, I'm not sure how to do this.

Can someone please briefly explain this to me or supply me with a link to a tutorial that explains how to do it?

Thanks very much,
Rudy

[Palmito]

Hey,

Assuming you have unstreched linear images.

I would:
- Register both stacks with star alignment module
- Split RGB image (with the slipt RGB channel toolbar button).
- Do the same for new HaRGB, keeping only R channel.
- Apply Linear Fit on each extracted channel to match brigthest.
- Recombine new R, G and B, from what I understand preferably with LRGB Combination with L unchecked (more control with transfer function) rather than Channel Combination.


If you wish to push further you may also process luminance channel separately, by extracting it from your RGB image (assuming it is the best) with tool bar button. That will allow specific noise reduction and stretching. In that case LRGB combination is mandatory.


If you want to go even further, you can apply deconvolution, but that's not so easy.

[Rudy Pohl]

Hi Palmito,

This is just great! Thanks so much for taking the time to write this out.

Best regards,
Rudy

[Palmito]

Hi Rudy,

My pleasure

Clear skies and best regards