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IC1805 Heart Nebula

SHO Request for feedback
Constructive Critique Requested •8 replies•87 views
Soothsayerman avatar
Soothsayerman avatar
Hello,

This image is SII, HA, OIII and there are a few things I am not happy particularly the stars and another is the color.  In many images the blue is really blue and the reddish rusty color is red so I am not sure what is really correct.   Any thoughts would be greatly appreciated on those things and anything else. Have no concern about being too direct, I'll appreciate it.

Thanks
-Jack

https://www.astrobin.com/962fgp/B/
gmadkat avatar
gmadkat avatar
I can totally relate to that, adjusting SHO took a while for me to get used to! Can I ask how you processed the image? Also, for narrowband imaging in general and for the Heart nebula, I use the Hubble palette using SHO, and work from there to get the blue and red tones by adjusting the colors. I typically do this using either the CurvesTransformation in Pixinsight or Photoshop which has more alternatives, like Camera Raw hue adjustment, or SelectiveColor and the color wheel to adjust green to bring our red and blue tones.  Either way, working in small steps iteratively works better for me than large changes.
Stars, I usually separate stars and reduce them or stretch separately to use a lower star stretch. 
There are other approaches, I just shared a few that I use for SHO!
Hope that helps!
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Uwe Deutermann avatar
Uwe Deutermann avatar
Hi Jack! I totally "feel" with you about the color problem, I fought (and still fight) this as well. Just look at my old SHO images, yup, same problems to see. So how to get the more pleasing color assignments? And … looking at your image I see also that star processing needs to be adjusted a bit (IMHO!). Gowri above mentioned already that the separation of stars and nebula is a method that can be recommended. Less stretch of the star only image, more on the nebula, and then recombining. Believe me though that this sounds easier than it is, a lot of trials will come up to make it look best.
About the color assignments: the raw SHO is always strange looking, so much green since Hα is most of the times dominant. I can recommend to watch some YouTube videos about the Hubble palette processing, they give you some good advices. Personally I like to use PS for this, and mostly because the color calibration in PS is nicer. If you own PS I can pass you my macro that I wrote for the adjustment. It usually works very well and requires not much post adjustments.
Uwe
Helpful Engaging Supportive
Soothsayerman avatar
Soothsayerman avatar
gmadkat:
I can totally relate to that, adjusting SHO took a while for me to get used to! Can I ask how you processed the image? Also, for narrowband imaging in general and for the Heart nebula, I use the Hubble palette using SHO, and work from there to get the blue and red tones by adjusting the colors. I typically do this using either the CurvesTransformation in Pixinsight or Photoshop which has more alternatives, like Camera Raw hue adjustment, or SelectiveColor and the color wheel to adjust green to bring our red and blue tones.  Either way, working in small steps iteratively works better for me than large changes.
Stars, I usually separate stars and reduce them or stretch separately to use a lower star stretch. 
There are other approaches, I just shared a few that I use for SHO!
Hope that helps!

* I did a histogram stretched of the 3 channels in Siril, removed gradients, set black levels, then combine the sho into rgb where I adjusted the channels  individually for color balance etc. did noise reduction, then combined them and did more adjustments. I may have done a tgv de noise in pixinsight and tried to do a photometric calibration in pixinsight but I couldn't get a plate resolve.

I used star exterminator and removed all the stars but it left artifacts that I wasn't happy with.   So I created a star mask in photoshop and I wasn't happy with that either.

At what point do you extract the stars in your workflow?
Soothsayerman avatar
Soothsayerman avatar
Uwe Deutermann:
Hi Jack! I totally "feel" with you about the color problem, I fought (and still fight) this as well. Just look at my old SHO images, yup, same problems to see. So how to get the more pleasing color assignments? And ... looking at your image I see also that star processing needs to be adjusted a bit (IMHO!). Gowri above mentioned already that the separation of stars and nebula is a method that can be recommended. Less stretch of the star only image, more on the nebula, and then recombining. Believe me though that this sounds easier than it is, a lot of trials will come up to make it look best.
About the color assignments: the raw SHO is always strange looking, so much green since Hα is most of the times dominant. I can recommend to watch some YouTube videos about the Hubble palette processing, they give you some good advices. Personally I like to use PS for this, and mostly because the color calibration in PS is nicer. If you own PS I can pass you my macro that I wrote for the adjustment. It usually works very well and requires not much post adjustments.
Uwe

*Do you extract the stars before you stretch?  then stretch the .fits file? or stretch, remove gradients, noise reduction then extract the stars?   Do  you use Star exterminator or photoshop to remove the stars or pixinsight?  I'm not  sure my workflow is correct.  Sure you can email me a script to [email]davidwjonesusa@gmail.com[/email]   Thanks!
gmadkat avatar
gmadkat avatar
I typically use StarXTerminator after I do the initial stretch. I have not had a lot of success with linear star removal in the past but it is supported.  Have you tried StarNet2 as an alternative?
Well Written
Soothsayerman avatar
Soothsayerman avatar
gmadkat:
I typically use StarXTerminator after I do the initial stretch. I have not had a lot of success with linear star removal in the past but it is supported.  Have you tried StarNet2 as an alternative?

*I have not tried starnet2 but I will give that a try thanks!
Uwe Deutermann avatar
Uwe Deutermann avatar
*Do you extract the stars before you stretch?  then stretch the .fits file? or stretch, remove gradients, noise reduction then extract the stars?   Do  you use Star exterminator or photoshop to remove the stars or pixinsight?  I'm not  sure my workflow is correct.  Sure you can email me a script to [email]davidwjonesusa@gmail.com[/email]   Thanks!


Always after the stretch, at various times of the stretch, hence I usually do it early in the stretch for the stars, and at the end for the nebula. I use StarXTerminator (in PI), for me the best tool for that, although Starnet++ is also not bad. Removing gradients and noise reduction always at linear stage. Here the macro steps for PS, post it here so that everybody who reads it can try it out 😊:



Uwe
Soothsayerman avatar
Soothsayerman avatar
Uwe Deutermann:
*Do you extract the stars before you stretch?  then stretch the .fits file? or stretch, remove gradients, noise reduction then extract the stars?   Do  you use Star exterminator or photoshop to remove the stars or pixinsight?  I'm not  sure my workflow is correct.  Sure you can email me a script to [email]davidwjonesusa@gmail.com[/email]   Thanks!


Always after the stretch, at various times of the stretch, hence I usually do it early in the stretch for the stars, and at the end for the nebula. I use StarXTerminator (in PI), for me the best tool for that, although Starnet++ is also not bad. Removing gradients and noise reduction always at linear stage. Here the macro steps for PS, post it here so that everybody who reads it can try it out 😊:



Uwe

Thank you Uwe, that gives me some insight and I will use that method.   Thank you both for your thoughts I really appreciate it!
Well Written Respectful