Leo Triplets LRGB

[Rodd]

This is my last image using the Televue np101is for a while--I have made the switch to the C11edge.  As usual, I find LRGB godawful hard.  I struggle with background, gradients, star color--you name it.  I would think there is something wrong with the scope (or camera), but narrowband data looks good (at least better).  So that seems unlikely.  I do have pretty sever light domes in the east and south, and seeing is rarely good.

This image contains about 29 hours of data in 10 minute subs--6 hours each in RGB and about 11 hours of lum. Taken with Televue np101is at F4.3, SBIG STT-8300 with self guiding filter wheel and Astrodon series e filters.  I had thought that the tidal tail would have come out a bit brighter considering the amount of data and the focal ratio.  I guess darker skies are needed.  Any criticism would be greatly appreciated--I need all the help I can get.  The image does looked a bit clipped in the black point--but the histogram is nowhere near the left hand edge--besides, this was needed to bring out what tidal tail there is.  It was a balance between too black of a background and too dim of a tidal tail.

 

[cfpendock]

Nice detail, Rodd, and the 29 hours clearly paid off at least you can see the tail.  Although where you got the 29 hours from I don't know.  I am pretty sure that we haven't had 29 hours of clear sky here this year.....

Chris

[Rodd]

20 minutes ago, cfpendock said:

Nice detail, Rodd, and the 29 hours clearly paid off at least you can see the tail.  Although where you got the 29 hours from I don't know.  I am pretty sure that we haven't had 29 hours of clear sky here this year.....

Chris

Thanks Chris--wow, looking at this image for the first time on my desk top and the background looks worse than i thought! Looks good on my 4k processing screen. I just can't figure it out for LRGB.  The 29 hours was collected over almost 2 months!  A night here, a night there.  It has been terrible weather

[Knight of Clear Skies]

Great detail and nice tails. The blue patterns on the background could well be a bit of IFN, might be worth checking against this IR dust map to see how well it matches up. It's come out a very deep blue though, I'm not sure that's its natural colour.

[Rodd]

17 minutes ago, Knight of Clear Skies said:

Great detail and nice tails. The blue patterns on the background could well be a bit of IFN, might be worth checking against this IR dust map to see how well it matches up. It's come out a very deep blue though, I'm not sure that's its natural colour.

Thanks Knight. I was thinking that maybe (hopefully?) some of what appears in my background may very well be the 4.3FL and duration of subs picking up faint stuff that really IS there--perhaps the IFN.  The color is strange--my histogram has all colors perfectly aligned so there is nothing too out of whack.  LP gradients?  Not sure.  

[Rodd]

I improved the background as well as the details of the galaxies--dust lanes are clearer and the stars are cleaner.  I lost the tail though--oh well.

[wimvb]

Great image (I like v 1 better, because of the tidal wave). The haze around the brightest srars shows the sky conditions you must have been fighting with. I think that even on 'clear' nights, there's enough moisture in the air to cause the sky to brighten up slightly, and make imaging difficult. At least in my neck of the woods, nights haven't been as dark and crisp as the can be.

Thanks for sharing

[ollypenrice]

You got the tail! That alone is a feat.

When you stretch really hard, do you at some point pin the background sky where it is and stretch only above that? I'd give it a try. It stops you dragging the background out to destruction. In this case you'd have to be very careful to put the pins (anchor points) below the faintest hints of the tail and lift immediately above them.

Personally, on this kind of image I do as above and get the background to 23/23/23 in RGB (Ps colour sampler tool, 3x3 average.) This also gives massively stretched stars. I thene start a new version from scratch, stretching gently and mostly at the bottom to get the sky up to 23/23/23 but with small galaxies and stars. I paste this on top and then erase it wherever there is galaxy, faint fuzzie or tidal tail. Provided the backgrounds are the same it will be seamless.

Olly

[Barry-Wilson]

Well done Rodd: lovely Triplet.

Thie revised image has a much better background without the blue areas.  The star top left certainly has some remnant blue halo hovering in the background.

[wimvb]

Since the background in the 1st version mainly seems to have colour variation, you could try just decreasing colour saturation for the background. Use a luminance copy of the stretched image as a mask, protecting the galaxies and the stars, and turn the saturation down. The procedure is basically the same in any processing software. You can probably also use the noise reduction technique discussed by Olly recently.

One of the deeper images of this area is by Fabian Neyer ( http://www.starpointing.com/ccd/leotriolarge2.html ). That image doesn't show any IFN or other dust in the background, so you wouldn't kill any valid data, whatever method you use to subdue the background.

Here's an example. Testing on your image, a combination of unmasked curves stretching à @ollypenrice, and masked colour desaturation, cleans the image very nicely.

(the test was done on your posted jpeg, it should work even better on the original)

[Rodd]

11 hours ago, ollypenrice said:

You got the tail! That alone is a feat.

When you stretch really hard, do you at some point pin the background sky where it is and stretch only above that? I'd give it a try. It stops you dragging the background out to destruction. In this case you'd have to be very careful to put the pins (anchor points) below the faintest hints of the tail and lift immediately above them.

Personally, on this kind of image I do as above and get the background to 23/23/23 in RGB (Ps colour sampler tool, 3x3 average.) This also gives massively stretched stars. I thene start a new version from scratch, stretching gently and mostly at the bottom to get the sky up to 23/23/23 but with small galaxies and stars. I paste this on top and then erase it wherever there is galaxy, faint fuzzie or tidal tail. Provided the backgrounds are the same it will be seamless.

Olly

Thanks Olly--I tried desaturating the background and it worked--I The other things you mention will take me a bit of thinking to figure out.  PS and PI take a bit effort to bring together (especially when one is totally ignorant of ps . I think the attached image has a pretty flat background as far as chroma.  And, the tail is back--so I think its a win win.  Galaxies are a tad less defined, but they are still pretty clear.  Their color may be a bit off, but I think I can live with it.

 

12 hours ago, wimvb said:

Great image (I like v 1 better, because of the tidal wave). The haze around the brightest srars shows the sky conditions you must have been fighting with. I think that even on 'clear' nights, there's enough moisture in the air to cause the sky to brighten up slightly, and make imaging difficult. At least in my neck of the woods, nights haven't been as dark and crisp as the can be.

Thanks for sharing

Thanks Wim--but the attached image has both a flat background and the tail is back (though not quite as bright).  Also galaxies are a bit less clear. I guess it can't be perfect.

 

6 hours ago, Barry-Wilson said:

Well done Rodd: lovely Triplet.

Thie revised image has a much better background without the blue areas.  The star top left certainly has some remnant blue halo hovering in the background.

Thanks Barry--I think I did not take it far enough though.  See attached. 

 

3 hours ago, wimvb said:

Since the background in the 1st version mainly seems to have colour variation, you could try just decreasing colour saturation for the background. Use a luminance copy of the stretched image as a mask, protecting the galaxies and the stars, and turn the saturation down. The procedure is basically the same in any processing software. You can probably also use the noise reduction technique discussed by Olly recently.

One of the deeper images of this area is by Fabian Neyer ( http://www.starpointing.com/ccd/leotriolarge2.html ). That image doesn't show any IFN or other dust in the background, so you wouldn't kill any valid data, whatever method you use to subdue the background.

Here's an example. Testing on your image, a combination of unmasked curves stretching à @ollypenrice, and masked colour desaturation, cleans the image very nicely.

(the test was done on your posted jpeg, it should work even better on the original)

Thanks Wim--that shot of the curve explains it well--I did not understand the shape until you showed me.  I will try that.  meanwhile I desaturated the background almost completely.  This version has a much better background, decent stars, and the tail is back (though dim).  galaxies are not quite as good--but still ok.  I guess it is a step in the right direction

[Rudeviewer]

WoW that is really awesome.  One of the best i have seen for detail on this trio.

[Rodd]

3 minutes ago, Rudeviewer said:

WoW that is really awesome.  One of the best i have seen for detail on this trio.

Thanks Rudeviewer,

  I was surprised at how much detail was able to be resolved in the dust lanes with a 4" scope.  I am sure there is more!

Rodd

[gorann]

Interesting thread about an outstanding image! Well worth the 29 h!

You managed to get a very even background in the last version but I now see a pink tint to the stars and galaxies (could be my monitor). I liked their colours better in the first versions and it may be easily fixed with some hue / saturation (or whatever you use in PI).

[Rodd]

5 hours ago, gorann said:

Interesting thread about an outstanding image! Well worth the 29 h!

You managed to get a very even background in the last version but I now see a pink tint to the stars and galaxies (could be my monitor). I liked their colours better in the first versions and it may be easily fixed with some hue / saturation (or whatever you use in PI).

No--there is a deep seated problem with this image.  I am tired of trying to "fix" it.  i need to root out the problem--which I have been trying to do ever since I started especially with Broad Band data.  

[gorann]

13 minutes ago, Rodd said:

No--there is a deep seated problem with this image.  I am tired of trying to "fix" it.  i need to root out the problem--which I have been trying to do ever since I started especially with Broad Band data.  

Yes, something happened there. I now see that the big star to the left has completely changed colour in your last version, from yellow to reddish-pink. Maybe you should have a look at other Triplet images to see what colours to expect.

You have fantastic data and I am sure you will get to the roots of the problem! I do not think it is you equipment and if you want, you could post your stacked data here and see what some of the SGLers can make out of it.

[wimvb]

Here's my attempt at your jpeg. Hope you don't mind.

I tested the above technique with curve transformation, but found that it makes the image simply too plastic (flattening the curve kills all noise and a few galaxies in the background, making it look very artificial). So I just extracted the Luminance and used this (after stretching and blurring) as a mask, to protect the stars and galaxies. Then I desaturated the background (though not 100%). Quite crude, but it did manage the colour variation, without affecting the stars, tidal tail or the faint fuzzies too much.

What processing software do you use? I think that DBE in pixinsight should be able to remove the effect before doing any other processing.

[Filroden]

1 hour ago, Rodd said:

No--there is a deep seated problem with this image.  I am tired of trying to "fix" it.  i need to root out the problem--which I have been trying to do ever since I started especially with Broad Band data.

I likewise struggle processing LRGB data. Are you doing your background extraction on the individual channels then combining them or combining then extracting? There seems to be two approaches to this and I've found getting the extraction wrong on individual channels can lead to some vary funky coloured remaining background. For me, removing any background is the single most difficult step in the process. Get it right and the rest of the process almost takes care of itself. Get it even slightly wrong and I find I'm wrestling the data. I've so much enjoyed using the new Ha filter as it starts from that nice, pristine background right out of integration

Your data is amazing and worthy of a lot of work and re-work getting it the way you like it.

[Rodd]

1 hour ago, wimvb said:

Here's my attempt at your jpeg. Hope you don't mind.

I tested the above technique with curve transformation, but found that it makes the image simply too plastic (flattening the curve kills all noise and a few galaxies in the background, making it look very artificial). So I just extracted the Luminance and used this (after stretching and blurring) as a mask, to protect the stars and galaxies. Then I desaturated the background (though not 100%). Quite crude, but it did manage the colour variation, without affecting the stars, tidal tail or the faint fuzzies too much.

What processing software do you use? I think that DBE in pixinsight should be able to remove the effect before doing any other processing.

That's an improvement.  I use PI--DBE is the source of many of my troubles--it often has a really bad effect on the image.  I have tried so many settings I find it hard to believe the answer lies with trying new settings.   It is LRGB that gives me this problem.  

[Rodd]

1 hour ago, Filroden said:

I likewise struggle processing LRGB data. Are you doing your background extraction on the individual channels then combining them or combining then extracting? There seems to be two approaches to this and I've found getting the extraction wrong on individual channels can lead to some vary funky coloured remaining background. For me, removing any background is the single most difficult step in the process. Get it right and the rest of the process almost takes care of itself. Get it even slightly wrong and I find I'm wrestling the data. I've so much enjoyed using the new Ha filter as it starts from that nice, pristine background right out of integration

Your data is amazing and worthy of a lot of work and re-work getting it the way you like it.

I agree with the background assessment. I went to a PI seminar and they seemed to think that using DBE after integration was the best way.  I find if I try to DBE the individual stacks, I run into trouble even faster--though I do DBE the RGB image and the Lum stack to be used for lum insertion separately--but using the same DBE icon (same settings and point placement).  Its funny--but my narrowband subs almost need no calibration even, and the background is never as hard as it is with LRGB.

Rodd

[wimvb]

You may know this already, but there are two ways dbe is generally used. One is few samples to remove very gradual gradients. The other is a lot of samples, closely spaced. In this case, I would use the latter method.

Btw, there is a darker patch at the very bottom of your image, and around the top galaxy.

[Rodd]

13 minutes ago, wimvb said:

You may know this already, but there are two ways dbe is generally used. One is few samples to remove very gradual gradients. The other is a lot of samples, closely spaced. In this case, I would use the latter method.

Yes--that is what I did-I used the generation button and it filled the image with points.  Then  I go through each point to make sure they were not on stars or galaxies (including the tail).  I also tried teh other approach, but in this image more points worked the best.  I tried many settings.  It worked up to a point, but there is still a color mottling in the background.

[wimvb]

My last guess would be light pollution. It affects nb much less, and you wrote in your original post, that you have light pollution at your site. Otoh, I believe that Göran has dark skies, which makes imaging and processing a lot easier. I have access to both a light polluted and a dark site, and can achieve a lot more and easier at my dark site.

[Rodd]

10 minutes ago, wimvb said:

My last guess would be light pollution. It affects nb much less, and you wrote in your original post, that you have light pollution at your site. Otoh, I believe that Göran has dark skies, which makes imaging and processing a lot easier. I have access to both a light polluted and a dark site, and can achieve a lot more and easier at my dark site.

Is there a light pollution filter answer?  Not sure where I would insert it--would need a custom size probably

[wimvb]

Not that I know of. To reduce light pollution, you'd need narrower rgb filters. AfaIk, rgb filter sets are designed to have low transmission at the normal lp wavelengths (such as sodium and mercury). Adding a lp filter may not have much effect, but can introduce reflections.

One other thing I noticed when comparing your image with Göran's, is the star in the upper right galaxy in your image (lower right in Göran's). In Göran's image, the star is in front of a bright dust patch just next to the core. In your image, there is a distinct dark patch, with no dust. This indicates a misplaced sample in dbe.