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Starless Heart SHO

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#1 drmikevt

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Posted 18 September 2019 - 07:59 AM

** WARNING - this image contains green colors

 

I always get the best tips on this forum and the latest to open up new processing avenues for me was learning about Starnet++, an open source star removal AI.  I'm going to do the whole thing over and try my best to truly remove all evidence of stars, but as a first go I'm liking the results and will surely be revisiting a lot of old data.  Here's what I did:

-Drizzle (I had to shooting at 2.8 arcsec/pix, so no MureDenoise)

-DBE

-Deconv.

-Linear denoise

-Stretch to .1 background (very light stretch)

-Run through Starnet++ (which, thankfully, was trained on a system somewhat close to the one use for this image (small refractor and CCD) so the algorithm worked very well)

-Use PS (for the first time!!) to clean the images as best as I could.  I'm a total PS noob so I'm sure I can do better going forward.  Each image took about 6 hours, probably)

-Back in PI, stretch to .2 background

-Combine with modified SHO palette

-Curves, Color Mask, HDRMT, LHE, MLT sharpen, TVGDN, ACDNR

-Convert to ICC profile

 

Please feel free to comment.  If you don't look tooooo close, I think it looks pretty good for a first starless image.

 

get.jpg?insecure

Attached Thumbnails

  • HeartNebula_starless_web_small.jpg

Edited by drmikevt, 18 September 2019 - 08:20 AM.

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#2 BenKolt

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Posted 18 September 2019 - 11:35 AM

Mike:

 

That is nicely done.

 

I am not of the starless processing camp, so please forgive me for asking some questions about it out of my naivety.

 

Is it the goal of such processing to produce a neat, starless image such as yours in order to emphasize just the nebula and remove the stars altogether, or will the stars be added back in later after they undergo separate processing?

 

My current focus is on improving my processing with proper masks to protect or isolate the stars through the steps, but I'm still curious about what you starless folks are up to.

 

Thanks for the explanation!

 

Ben



#3 vehnae

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Posted 18 September 2019 - 03:17 PM

Personally I view the star removal as a perfect star mask (which it essentially is). You can then continue doing everything that you would usually do with the stars masked out.

 

Apart from making "regular stuff" easier it provides an easy way to de-emphasize the starfield because you can stretch the nebula and the stars separately and then combine them back together. But one has to be very careful when doing this in order to avoid visible artifacts.

 

  ++ Jari



#4 vehnae

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Posted 18 September 2019 - 03:18 PM

Oh, and the image is very nice too! I love the colours!

 

  ++ Jari



#5 elmiko

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Posted 18 September 2019 - 03:22 PM

Beautiful image! Color is really nice.

Mike



#6 drmikevt

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Posted 18 September 2019 - 04:02 PM

But one has to be very careful when doing this in order to avoid visible artifacts.

 

  ++ Jari

Thank you (I'm a big fan of your work).  I'm struggling with this as we speak.  I've created an HOO image with nice colored stars and want to overlay the stars on the image above.  I'm trying some different techniques with both Photoshop and PI.  I think I'll figure it out, but what do you do?



#7 vehnae

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Posted 18 September 2019 - 04:13 PM

I think I'll figure it out, but what do you do?

If you substract a starless image from the original, you are left with an image that contains only the stars. Then it is quite easy to construct a coloured image with just the stars and then add them back to the original image using PixelMath ("starless_image + stars_image") in PI or Linear Dodge (Add) in PS. If there is nebulosity present in the HOO image you can use the Screen -mode in PS, but the nebula colour will be affected depending on how bright it is. 

 

  ++ Jari


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#8 2ghouls

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Posted 18 September 2019 - 04:31 PM

Great job Mike! I especially like how the fish head came out here.



#9 drmikevt

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Posted 18 September 2019 - 04:32 PM

Is it the goal of such processing to produce a neat, starless image such as yours in order to emphasize just the nebula and remove the stars altogether, or will the stars be added back in later after they undergo separate processing?

Thanks!  I can only speak for me, of course, but I wanted to create an image that emphasized the nebula, yes, but that allowed me to stretch further then I'd be able to if there were stars present.  I could have stretched further but wanted to keep it a little broody and subdued (it is space, after all).  If you look on a-bin a lot of the starless images are stretched to background of 3 or more, which I think is a bit much but to each their own.  Commonly (almost all the time) stars are added back in after pushing the nebula as much as possible, and I think that's where I'll end up.  But, for this, I wanted to see if I could create an image with no star artifacts just to see what it would look like.  In the end, as I'm sure many can attest to, it takes an absolutely tremendous amount of tedious work to smooth out the artifacts left over from the star removal algorithm.  I think that if the intention is to add stars back in, you wouldn't need to put that kind of time in and could just deal with the most obvious stuff.  But, really, this image was more of a proof of concept than anything.  I like it and think I might be motivated to try again and make it cleaner, but we'll see.  



#10 drmikevt

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Posted 18 September 2019 - 04:49 PM

If you substract a starless image from the original, you are left with an image that contains only the stars. Then it is quite easy to construct a coloured image with just the stars and then add them back to the original image using PixelMath ("starless_image + stars_image") in PI or Linear Dodge (Add) in PS. If there is nebulosity present in the HOO image you can use the Screen -mode in PS, but the nebula colour will be affected depending on how bright it is. 

 

  ++ Jari

Wow  - I don't really want say this too loudly but that was SO much easier is PS then in PI - or, rather, the result was much cleaner.  At least for me.  Here's a light touch of some HOO stars added.  

Attached Thumbnails

  • SHO_HOOstars_sm.jpg

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#11 Tayson82

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Posted 20 September 2019 - 07:40 AM

Very nice photo! Cool!

Coud You tell a litte more about it?

 

-Combine with modified SHO palette

-Convert to ICC profile


Edited by Tayson82, 20 September 2019 - 07:41 AM.


#12 drmikevt

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Posted 20 September 2019 - 10:03 AM

Very nice photo! Cool!

Coud You tell a litte more about it?

Hi.  In reference to the items you mention:

 - Modified SHO palette:  I stretched each S,H,O master frame to the exact same background (.2) and then used PixelMath to combine the images.  A pure SHO combination actually looked pretty good, but I thought that colors were better with a modified palette.  Here's what I used:

R:  S*.8 + H*.2

G:  H*.8 + S*.2

B:  O

Usually, if I don't use the mix above, it will be somewhere in between that mix and the one below.  If you are using numbers that add up to 1 or more, its a good idea to check the 'rescale' box.  Sometimes, if you are close to over exposed, it is better to use totals that don't add up to one to avoid clipping the whites.  

R:  S*.7 + H*.3

G:  H*.7 + O*.3

B:  O*1.2

 

ICCProifle: I am NOT an expert on this, but think I understand that converting the image's ICC Profile (which contains some sort of information about how colors are displayed) to the web's standard of sRGB IEC61966-2.1 allows the image to be more accurately displayed on sites like Astrobin. So, after the image is finished, I duplicate it, call it 'Imagename_web' and use the ICCProfileTransformation process to change the ICC Profile.  Then, I use Rescale to make the image 300dpi.  Then save as JPEG for Astrobin at 100%. 

 

I hope this helps!


Edited by drmikevt, 20 September 2019 - 10:04 AM.

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#13 2ghouls

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Posted 20 September 2019 - 11:41 AM

Wow - I don't really want say this too loudly but that was SO much easier is PS then in PI - or, rather, the result was much cleaner. At least for me. Here's a light touch of some HOO stars added.

Yep, blending stars back in with PS is so easy and great. To do it in PI the same way you need a fairly complex pixelmath formula. I use both PI and PS (and now APP too). They all have their own strengths.

#14 drmikevt

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Posted 23 September 2019 - 12:21 PM

Just to finish out this thread.  I went back and more carefully added some HOO stars onto the SHO starless image.  At the compression needed for this forum, it may look the same as the starred image above, but is actually much cleaner.  If anyone wants to see it, the link is below.  I also want to show what the Starnet++ algorithm can do all by itself.  Below is the HOO image and the raw output of Starnett++.  Not bad!

 

get.jpg?insecure

 

 

Attached Thumbnails

  • HOO_Starnet.jpg



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