L ,Ha rgb

Questions and answers about processing in StarTools and how to accomplish certain tasks.
Ricker
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Re: L ,Ha rgb

Post by Ricker »

I have used some of these methods. Would it be possible to add additional filters into the compose image tool.
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admin
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Re: L ,Ha rgb

Post by admin »

lemmu wrote: Wed Nov 11, 2020 4:21 pm Quick answer is for more detail. I have seen added Ha subs to M31 to enhance star forming regions in spiral arms. Those images are really stunning.
Ok.
Galaxies typically don't show up well in Ha, so using a galaxy's Ha for luminance (detail) is not advised. You actually spent most of your time acquiring Ha, which would have been better spent acquiring L/luminance for this particular target.

For this target, you will want to add Ha to the red channel for the purpose of chrominance only. E.g. this will make areas where Ha is strong "extra red", but will not modify detail (luminance). This approach gives you the best of both worlds with easily distinguishable HII areas, yet still showing all other details in exactly the same way would expect them to look in the visual spectrum.

Per the previous posts, to add Ha to R, you can either use the Compose module to create a new composite of R+Ha, save that and re-open it as your "new" R. Or you can use the Layer module for the same purpose.

When you create your "final" composite with everything combined, be aware that adding your new red (Ha+R) channel for the purpose of synthetic luminance doesn't make a whole lot of sense due to the Ha component in your new red channel (adding narrowband signal to wideband signal doesn't make a whole lot of sense). I would either use "L, RGB" for "Luminance, Color" (e.g. no synthetic luminance at all), or you could create a new L dataset that contains the synthetic luminance of L + R + G +B (e.g. not Ha), save that and use that as your new luminance for "L, RGB".

Regardless of what you choose, once everything is combined, just process as normal.

So, to recapl

Here I am creating a synthetic luminance frame from L + R + G + B;
StarTools_248.jpg
StarTools_248.jpg (102.64 KiB) Viewed 466 times
I keep that, and save it.

Here I am creating a new red channel Ha + R (using equal exposure times here);
StarTools_249.jpg
StarTools_249.jpg (101.55 KiB) Viewed 466 times
I keep that, and save it.

Now I put everything together;
StarTools_250.jpg
StarTools_250.jpg (120.66 KiB) Viewed 466 times
And then process it using a (fairly) standard workflow;
NewComposite.jpg
NewComposite.jpg (328.06 KiB) Viewed 466 times
Hope this helps!
Ivo Jager
StarTools creator and astronomy enthusiast
lemmu
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Re: L ,Ha rgb

Post by lemmu »

Hi Ivo, Thanks a buntch! :bow-yellow: Truly helpful. I'm waiting for the reducer, I'll reshoot the whole galaxy and process as suggested. Cloud magnet is still working now ,so by X-mas I can perhaps post something what I achieved. :roll:
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Re: L ,Ha rgb

Post by admin »

lemmu wrote: Tue Nov 17, 2020 5:53 pm Cloud magnet is still working now ,so by X-mas I can perhaps post something what I achieved. :roll:
:lol:
The pain is real...
Ivo Jager
StarTools creator and astronomy enthusiast
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