HaRGB processing... whats happening here?

[StargeezerTim]

Hi all, this is a HaRGB process of NGC 7822 that I can't get a decent finish on. When I combine the Ha as luminence with the RGB (inc 50% Ha in red channel) at about 75% I get this sort of greenish pale stuff where once was red nebulosity (e.g. the nebula to the left of the image) when I try and remove the green I get some weird colours. Using the colour sampler tool at the space in the bottom right showed RGB figures of 30,30,30, but it looks really brownish to me. I havn't had the same problems with other images, at least not to this extent and wondered if anyonen has any ideas of a) what caused it,  how to process and add the Ha so it gets better colours?

The process I used is based on this tutorial.

https://starizona.com/acb/ccd/software/ps_hargb.aspx

I added the Ha to the red channel at 50%, it was even worse when using the 20% (80% Ha) proportion recommended in the tutorial. The seeing wasn't particularly good when capturing the data. Mushy skies and a bit dewey...

Cheers, Tim. 

 

[Thalestris24]

Hi

I can't really advise I'm afraid as I don't have the expertise. I'm wondering, though, which camera you imaged with as you don't seem to have a mono cam listed in your sig? Doesn't the HaRGB technique depend on having a separate mono/luminance image? (Since that's where all the image detail is). If you actually used a dslr then what was your pre-processing workflow? 

Louise

[StargeezerTim]

9 hours ago, Thalestris24 said:

Hi

I can't really advise I'm afraid as I don't have the expertise. I'm wondering, though, which camera you imaged with as you don't seem to have a mono cam listed in your sig? Doesn't the HaRGB technique depend on having a separate mono/luminance image? (Since that's where all the image detail is). If you actually used a dslr then what was your pre-processing workflow? 

Louise

Hi Louise, I used an Ha filter for luminence and the rgb was the 'normal' dslr image. Tim.

[Thalestris24]

1 hour ago, StargeezerTim said:

Hi Louise, I used an Ha filter for luminence and the rgb was the 'normal' dslr image. Tim.

Hi again

Oh ok - then that's probably why your results are maybe not as good as you hoped. You can only get true 'luminance' from a mono camera. Things might be better if you broke the raws down to r, g, g, b, and Ha before stacking though then you'll be downsizing the image size i.e. only 1 in 4 pixels are red/Ha. You can do it in IRIS which is free. Funnily enough I have some Ha images to process myself (some taken on a modded dslr) though I probably won't do HaRGB. I'm not sure it's worth the effort to attempt HaRGB from dslrs. Certainly worth it if you have a mono camera for the Ha

Louise