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Have you tried Vicent's Continuum Ha blending technique

JeffJeff
in PixInsight
Hello Adam,

I recently subscribed to Horizons and had not got to any of your Ha blending techniques, but I did try your StarNet blending fixing star halos later in my workflow which I will get to later in my post.

Last year I captured about an hour of integration time on NGC 281 with an OSC while I was killing some time waiting for my primary target.  The data was rather weak so last week while I was killing time waiting for my primary target to rise, I collected 5 hours over two nights of Ha on NGC 281 that I planned on blending with the OSC data from last year.   I took the Ha data with my mono CCD camera.   I decided to give Vicent's Ha blending using a continuum map a try.   I was able to successfully do the first part which was the continuum map but I did 6 iterations because my RGB was weak.  The second part which was transferring the a/b  lab channels of the HaRGB from the continuum map method to an HaGB image did not work out for me because I think my Ha was too strong so I just resorted to separating the Lum channel from my HaRGB and blending the extracted lum channel with with a starless Ha using Screen.  Then I processed the Lum and RGB (HaRGB) as per the standard work flow.  I am curious to know your thoughts about Vicent's blending technique and if you have tried it. 

Here is my result:  https://astrob.in/u9f491/D/

You can see the original RGB there as well.  So after dong the LRGB combine which I did soft stretches on before combining, I then used your Blending with StarNet and star halo removing technique.  It took me several tries to get something somewhat acceptable and still had some yellow cast around the yellow/orange stars that I had to clean up using ColorMask and desaturation.  This was even after doing a 50% screen blend.   Just curious to know what you might think about my efforts in using this technique.

The RGB data in this image is sub par for me but it was a good exercise in learning new techniques.   The main issue I had with the StarNet blending with halo fixing technique is doing that in a field with nebulosity.   If the RGB was deeper I think it would have been more difficult or perhaps not appropriate to do.  I was going to ask you what you did for nebula images but then I realized I can just watch your Horizon processing examples.  I see you have some nebula images there but I had not had a chance to watch them yet as I am still going through your standard Horizon lessons.   Thanks a bunch.  


Comments

  • BlockHeadBlockHead
    Jeff,

    if you recall I created a 'smoothed" - but it contained the local sky color information. If you do not keep enough of that information- you will indeed have a color mismatch. Remember, screen blending means that if you make anything black in a layer- it will not show. Thus, if you actually made black bits around the star remnants in the starless image- all you will see if the original (other layer) data.
    So again, it is important to choose the right level of MLT to get the right local information. 

    The image I just posted of M78 is full of nebulosity and the technique worked out well. 

    There are no prefect methods though. Each image requires its own adjustments. 
    I am familiar with Vicent's method(s)- however, if people complain about my level of complexity- they haven't seen Vicent's stuff! 

    -the Blockhead



  • JeffJeff
    Thank you Adam.  I was afraid to touch the stars in the nebula.  I will need to practice your technique some more to get the hang of it.   Your comment about Vicent's complexity made me laugh as he mentions his technique to be a "simple citizen".  I don't find your processes to be complex but they require certain observational and artistic skills that I need to develop. 
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