Veil nebula

[scotty38]

Despite the lack of darkness I thought I'd have a go at a bit of imaging so here is a couple of hours I took last night. Nothing done to it other than stretch in PI but quite pleased with how it turned out, I really didn't expect to see much so might have a go at this one...... 😀

 

[scotty38]

Tried star reduction using PixelMath for the very first time....

[geeklee]

Nice one @scotty38 I like that first one with the mega star field and the veil just coming through, but the second is good too.  Somewhere in between perhaps?  

[scotty38]

Thanks , appreciated. I'm trying to get to grips with PI so was trying to see if there was more nebula to get out of it but I think I need a few more tutorials 😃

On the second one I created a star mask and then added 0.2 of it to the normal image to try and reduce the stars a little but it clearly did more. What I don't know yet is if that's the right way to do it or if my Jedi skill with Pixelmath is letting me down 😂

[Budgie1]

Try Morphological Transformation for star reduction. 

These are the settings I use to reduce by 30%. Adjust the "Amount" slider to where you want to be.

Another thing to try;

After the image has been stretched, create a star mask using StarNet on the colour base image, so you remove all the stars. Create a clone if you don't want to try it out on your main image. Then you can work on the nebula and background separately to the stars. 

You can then use curves - saturation on the stars to bring out the colour you want and reduce them with Morphological Transformation, before adding them to the background again with Pixelmath.

Have a play and see how you get on.  

[geeklee]

9 hours ago, scotty38 said:

On the second one I created a star mask and then added 0.2 of it to the normal image to try and reduce the stars a little but it clearly did more. What I don't know yet is if that's the right way to do it or if my Jedi skill with Pixelmath is letting me down 😂

There are so many ways to perform star reduction - sometimes different methods will suit certain images or goals better.

@Budgie1 described a couple of methods above.  Within MorphologicalTransformation I like the Morphological Selection  Operator - this has a blend of erosion & dilation based on the Selection setting.  Less than 0.5 will favour erosion.  You can tweak the Amount  and Iterations too.  Obviously need to look at the Size element as well.

MT should be used with a StarMask, but you can also use the contours element of the StarMask.  Here's a good tutorial to start with:

https://www.lightvortexastronomy.com/tutorial-reducing-star-sizes.html

Edited June 14, 2021 by geeklee

[scotty38]

7 hours ago, Budgie1 said:

Try Morphological Transformation for star reduction. 

These are the settings I use to reduce by 30%. Adjust the "Amount" slider to where you want to be.

Another thing to try;

After the image has been stretched, create a star mask using StarNet on the colour base image, so you remove all the stars. Create a clone if you don't want to try it out on your main image. Then you can work on the nebula and background separately to the stars. 

You can then use curves - saturation on the stars to bring out the colour you want and reduce them with Morphological Transformation, before adding them to the background again with Pixelmath.

Have a play and see how you get on.  

Thanks will give it a try. I did actually do that with Starnet but then didn't know how to get stars back in the starless image so used the mask against the original image with stars...... Lot to learn but what I didn't think of doing was enhancing the nebula in the starless image, then again as mentioned I didn't know what to do with it afterwards.

Edited June 14, 2021 by scotty38

[scotty38]

2 minutes ago, geeklee said:

There are so many ways to perform star reduction - sometimes different methods will suit certain images or goals better.

@Budgie1 described a couple of methods above.  Within MorphologicalTransformation I like the Morphological Selection  Operator - this has a blend of erosion & dilation based on the Selection setting.  Less than 0.5 will favour erosion.  You can tweak the Amount  and Iterations too.  Obviously need to look at the Size element as well.

MT should be used with a StarMask, but you can also use the contours element of the StarMask.  Here's a good tutorial to start with:

https://www.lightvortexastronomy.com/tutorial-reducing-star-sizes.html

Thanks for this too, I'll have a run through this evening and see what I can do. It's fascinating in itself the options there are with PI to do these things.

[Budgie1]

1 hour ago, scotty38 said:

I did actually do that with Starnet but then didn't know how to get stars back in the starless image so used the mask against the original image with stars...... Lot to learn but what I didn't think of doing was enhancing the nebula in the starless image, then again as mentioned I didn't know what to do with it afterwards.

This one is easy (when you know how).

With the background & star mask images open, right click on each image and click on "Identifier" then rename the image to something sort (I use BG for the background & SM for the star mask). Then, when you want to re-combine them, open Pixelmath and put in BG+SM into the top text box.

You can also choose whether to replace the original image or create a new one by expanding the "Destination" drop-down on Pixelmath. About half way down you'll see the default is "Replace target image", but you can change this to "Create new image" and this will leave the background & star mask alone and combine them into a new image. This allows you to see what it looks like and choose to keep the new combined image or ditch it and try something else with the originals.

Edited June 14, 2021 by Budgie1

[scotty38]

47 minutes ago, Budgie1 said:

This one is easy (when you know how).

With the background & star mask images open, right click on each image and click on "Identifier" then rename the image to something sort (I use BG for the background & SM for the star mask). Then, when you want to re-combine them, open Pixelmath and put in BG+SM into the top text box.

You can also choose whether to replace the original image or create a new one by expanding the "Destination" drop-down on Pixelmath. About half way down you'll see the default is "Replace target image", but you can change this to "Create new image" and this will leave the background & star mask alone and combine them into a new image. This allows you to see what it looks like and choose to keep the new combined image or ditch it and try something else with the originals.

Brilliant thank you that's great and I will give it a go....

Edited June 14, 2021 by scotty38

[david_taurus83]

9 hours ago, Budgie1 said:

Another thing to try;

After the image has been stretched, create a star mask using StarNet on the colour base image, so you remove all the stars. Create a clone if you don't want to try it out on your main image. Then you can work on the nebula and background separately to the stars. 

You can then use curves - saturation on the stars to bring out the colour you want and reduce them with Morphological Transformation, before adding them to the background again with Pixelmath.

Have a play and see how you get on.  

How do you find StarNet leaves the stars? It's great at removing them from nebulae but I often find the stars in their separate image are left with some weird hatch like artifacts. Do these artifact disappear if you add them back in with Pixelmath?

[scotty38]

Thanks again for all the tips and advice which I'm goiung to pore over this evening but I have a question...

I have been considering an Optolong L-Extreme filter so would that be beneficial to me for this type of image? I am in a Bortle 4 zone with zero light pollution from street lamps or neighbours if any of that is relevant by the way.

[Budgie1]

38 minutes ago, david_taurus83 said:

How do you find StarNet leaves the stars? It's great at removing them from nebulae but I often find the stars in their separate image are left with some weird hatch like artifacts. Do these artifact disappear if you add them back in with Pixelmath?

They do leave some artefacts behind and sometimes it takes brighter parts of a nebula or galaxy with it to the star mask. Most of the time these are corrected once the two are re-combined again, but occasionally this doesn't happen which is when it's best to just use a standard star mask. The other alternative is to use the CloneStamp to make corrections or a minor touch up in PS afterwards.

[Budgie1]

44 minutes ago, scotty38 said:

I have been considering an Optolong L-Extreme filter so would that be beneficial to me for this type of image? I am in a Bortle 4 zone with zero light pollution from street lamps or neighbours if any of that is relevant by the way.

With the L-eXtreme you will get better definition of the nebula and less pronounced stars but you have to be careful about which targets you use it on.

Because it filters everything except Ha and OIII to 7nm, it will block the light from planetary nebula, like the Iris nebula or NGC 2023 if you're imaging the Horse Head Nebula.

Here's the Horse Head with my ASi294 MC Pro with just a UV/IR cut filter and below is the same target with the L-eXtreme. Not the best images but a good demo.

I use the L-eXtreme when the Moon is near full because I live in a Bortle 2 area and the Moon just floods the image without it. You may be better going with the L-eNhance instead as it's not a restrictive.

[scotty38]

Thanks and that's a great example. I knew I'd have to be careful of the targets and I also have a UV/IR already. I was thinking it would help on the moon flooded images though and that was some of my reasoning.

This image of the veil for example, even thought it was a "bright summer nigh" there was no moon and there was very little gradient that my inexperienced eyes could see. Up until this one image I'd been battling with gradients and ABE/DBE in PI not seemingly working as well as it did for other folk. Finally getting an image that ABE/DBE seem to work well with made me think about a filter to kill the moon whenever it is up and about...

Edited June 14, 2021 by scotty38

[scotty38]

Just had an initial play with MT and blimey, thanks for this one 🙂

Not really understanding what the parameters are doing so just following an example above so far....

 

Edited June 14, 2021 by scotty38

[geeklee]

1 hour ago, scotty38 said:

Not really understanding what the parameters are doing so just following an example above so far....

I'm just wondering as I was pixel peeping this image, if the stars were masked?  It looks like everything has had MT applied which can give the image a mottled texture.  Left: new, right:old.  You can see the difference in stars though - gone or much smaller!  MT can be quite a subtle look, but like everything in PI, you can go to any extreme you want!

I did quick version on a small section of the top image.  You can go lighter.... or way stronger of course  

Contours star mask, MT, normal star mask, MT, little sharpening using normal star mask.

 

Edited June 14, 2021 by geeklee

[scotty38]

Thanks again and yes plenty to play with and get my head around, so many options it's mind boggling. Just to put you out of your misery though I applied the MT to my original file and not the one I'd done any masking on so apologies for any confusion.