RGB + Luminance + Ha - Processing question

[swag72]

I am working on an HaLRGB image (that is to say I have the data for it, but probably not the processing skills!!) - I have looked at the RGB data while I was waiting for some darks today.

I have a total of 15 x 300s in each RGB, which for a RGB image I know isn't much but combining Luminance and Ha as well should be enough from what I have read. Total data is in excess of 14 hours. So, as there's not masses of RGB there is some noise creaping into the background. Does the L and Ha mask any of this at all? Or should I not be pushing the RGB data so hard and just aiming for some colouration in the stars and Galaxy without messing up the background?

If it was just an RGB image, would I be processing it differently than planning on combining L and Ha?

Hope you can help as I am planning on giving this a go this evening

[steppenwolf]

I would suggest working on the Ha and Lum. channels to get the best looking mono image you can achieve. Process the RGB data gently and don't worry too much about the noise, just aim at pleasantly saturated colours.

Forgetting about the Ha for now - blending that is a totally different question - paste the Lum. on top of the RGB, set the blend mode to Luminosity and see how it comes out. If you feel the RGB is still showing too much of its own noise, simply select the RGB layer and Gaussian blur it, trying various different levels of blur.

You will be amazed at the result as the Lum. will retain the detail and provided you don't blur too far, the colour will remain unchanged but the colour artefacts will have gone.

[swag72]

Excellent - Thanks Steve!

[swag72]

Mmm, just added the Luminance and it really pulls the image down, it's clearer, sharper and more detailed as a straight RGB. Does this suggest that my L is bad? I took it at 420s and it was very much to the right of the histogram, although value in the galaxy were not above about 58000 ADU.