M16 Eagle nebula: Hubbled

[Uranium235]

Here is part one of what I got last night. I received my SII filter from FLO the other day so I was keen to try it out. Not before I had to deal with a little household emergency - an outdoor drain had blocked so I had to stick my arm down there to clear out the crud.... my god, the smell was enough to make you puke!

Anyways, the seeing started to clear up as the evening wore on so I managed to get the subs I needed to start doing a bit of hubble magic.

As predicted though, I have run into the old "magenta halo" problem due to the extreme stretching needed the SII frames require when doing HST colours. I know theres a way to fix it, but it will take a fair bit of messing with PS to sort it out.

Its my first bash anyway, so I cant be expected to get it bang on

M16: Eagle Nebula

12x300+10x600 (Ha_L), 12x300(SII_R), 12x300(Ha_G), 12x300(OIII_G)

ED80 (0.85x), Atik 314L+

Calib: Darks

Setpoint: -10

EDIT: Have reduced halos and posted orignial colour and classic HST gold versions.

Thanks for looking

First the "green" version, this is what first comes out of combining the SII/Ha/OIII channels.

Then the Hubble classic gold version made by playing with the select colour tool in PS.

[ollypenrice]

I think parts of this look really great but the colour is very much concentrated in the central region. I haven't tried the Hubble so I've no idea how it plays out.

Olly

[Uranium235]

Thanks Olly, Ive since posted a version with more saturation. But I think the concentration of colour may be a consequence of using so much Ha as the luminence channel. It sort of diluted the colour a bit when I merged the colour with the luminence, I'll see if i can fix it.

[martin_h]

Have you tryed it without a Lum Channel? I've not done many Hubble images but just use straight RGB.

Creating Hubble Palette Color Mapped Images

[Uranium235]

Martin, I dont think there is enough data to do straight RGB (would be too noisy), the only other way would be to get another 10x600 in OIII and SII, that would balance it out a lot better.

But, ive had yet another fiddle with it and reduced the Cyan saturation slightly so I can increase the saturation in the rest of the colours. I have included the straight SII/Ha/O3 "green" image, and the classic gold version. Will post that in a min.

[roundycat]

I'm with Martin here, why use Luminance? It seems to be very sharp and I think that is making the halos stand out more than they should.

Dennis

[Uranium235]

I'm with Martin here, why use Luminance? It seems to be very sharp and I think that is making the halos stand out more than they should.

Dennis

Hi Dennis,

The original thought behing using luminence was just me being tight and refusing to throw perfectly good Ha subs away when I could use them as part of a layer that would boost the detail

Since its my first go at this, I was treating it the same way I would an LRGB- ie: carry the detail in the luminence and do the NR on the RGB master. Youre right in that I might have introduced a fair amount of halos through too much sharpening, but ive tried to address this with a couple of updates (let me know if its any better please).

The only 2 stars that give me any trouble are the two on the left, I had trouble with those in HOO palette too (big red halos).

No doubt I will have yet another go at it, will post it a bit later if I come up with anything better.

[martin_h]

They look better, but I think it would be worth the extra time to grab a few more OIII / SII subs, becaues what you have there is good and a couple of hours more would make it great. Also with a bit more data you might be able to controll those two stars a bit more and not have to push the data to breaking point.

[Cloudwatcher]

Number 2 for me........... seems to have more depth if you know what I mean.

[roundycat]

the new one at the top looks about right for a raw Hubble palette pic, there should be some blue in the centre. If it is all green you will never get the right colour. The 'gold' version does look a bit garish somehow. Oversaturated?

The stars in all versions look like they don't belong, either they have been sharpened way too much or you are working on it in layers and one layer is getting a treatment the other(s) are not getting.

Are you by any chance using High Pass on the composite?

Dennis

[RobH]

Very nice detail in the central region....you obviously have some decent data there.

I would agree that you don't need a luminance layer, and I think you'll find it worthwhile to add some 10 minute subs to your OIII and SII to balance up with the Ha, then process without luminance.

I also agree with Dennis in that it looks oversaturated to me, and there is some sort of sharpening artifact around the stars, making them seem separate from the nebulosity.

What sharpening routine did you use, and did you apply it to the background only, or to the whole image?

Cheers

Rob

[Neilius]

Love the detail in both images. If only we could see that with the eye through the telescope!

[Uranium235]

Very nice detail in the central region....you obviously have some decent data there.

I would agree that you don't need a luminance layer, and I think you'll find it worthwhile to add some 10 minute subs to your OIII and SII to balance up with the Ha, then process without luminance.

I also agree with Dennis in that it looks oversaturated to me, and there is some sort of sharpening artifact around the stars, making them seem separate from the nebulosity.

What sharpening routine did you use, and did you apply it to the background only, or to the whole image?

Cheers

Rob

Hi Rob,

The sharpening routine was originally done with a mix of smart sharpen and noise reduction (which has sharpen detail within it), and was applied to the background layer only as I was only blending the colour from the colour master.

Ive since done it again, except without the smart sharpen. Additional processes were with noels actions (local contrast enhancement), noise ninja (lightly applied) and lastly the clarify command (in PSP), which were applied to the flattened image.

The dark halos around most of the stars have gone now, at the expense of a bit of sharpness. Ive backed off on the saturation a bit too - please let me know if its any better

I will make a start on adding some more OIII and SII tonight, might not be able to finish it all though being as its a Sunday night.

[roundycat]

It's only a vast improvement. People all over the place are making the mistake that the various filters available in Photoshop later versions are the route to instant success. Not so. Forget Smart Sharpen, you are much smarter than the software and smart sharpen was never intended for astro work. What on earth does 'Clarify' do?

Local contrast enhancement may well be a good plug in when used properly and I'm not suggesting you used it improperly but you can usually get better and more controllable effects using the basic tools. If you want to enhance the gas shock fronts High Pass in Photoshop was made for it. You do need to do it underneath a star layer. If you use High Pass on the stars the effect will make you feel suicidal.

See here: Astrophotography

Dennis

PS: if you ever use noise reduction make sure the sharpen option is OFF.

[AndyUK]

I think the rework looks great (as Dennis said, a case of less is more?). I'd certainly be VERY happy with it (if only I could get to it...)

(I can't wait to get the SII filter in the wheel, but it's been 11 days now since I had skies that I could get out in... )

[RobH]

That's a great improvement...well done.

Throw some more OIII and S2 at it and you'll have a corker of an image

I too am intrigued by the 'Clarify' command!!....What version of PS are you using?

Rob.

[Uranium235]

That's a great improvement...well done.

Throw some more OIII and S2 at it and you'll have a corker of an image

I too am intrigued by the 'Clarify' command!!....What version of PS are you using?

Rob.

Thanks Dennis & Rob

Ahh... Clarify - Thats a command in paint shop pro that more or less does the same thing as local contrast enhancement in noels actions - except that I have a more control over it. Its useful for bringing out dark globs and dust lanes. I will attach an example, but its just for illustration only - I wouldnt normally set it that high.

And being that PSP is only 8bit, I dont use it until the very end when all the donkey work has already been done by Photoshop.

I did manage to get more subs last night but im still 30min short in OIII and an hour short in SII, hope to finish it sometime this week.

PS: Thanks for the tips Dennis, I will give the star layer another go. I was trying to do it with selective colour but it always seemed to select bits of the nebula or fail to pick up the whole halo on some stars.... oh well, back to school for me!

[roundycat]

I think just about everyone will agree that Photoshop has a lot more to offer than PSP. For my money, going from PS to PSP is a bit like going from the fine oils to the tar brush when you are painting a masterpiece.

To extract a star layer:-

Duplicate the layer.

Set duplicate to Image - Adjustments - Threshold

Set the Threshold value to pick up most of the stars. OK.

Use the Magic Wand (W) and select the background which is all black.

Invert the selection.

Delete the Threshold layer

Expand the selection by 1 or 2 pix and Feather by 1. Depends on your star quality.

Make sure the background is the active layer (or the only layer)

Ctrl J to turn the selection into a new layer via copy.

You now have two layers, background and stars

Duplicate the background and set the blend to Overlay.

Filter - Other - High Pass and set to a value that needs thinking about. 4-10 pixels to start. Watch the halos on the Overlay layer, they will be grey and raising the radius will make them gradually disappear. The preview works as well.

Click ok

Switch the high pass layer on and off a few hundred times whilst studying the effect. You can drop the layer opacity if you feel the filter is too strong. Or go back and do it again.

Flatten it.

Work on the contrast/brightness/star colour etc.

Dennis

[Uranium235]

Thanks Dennis, I did a bit of practice with it last night and its actually quite good I will do this when I process the final version (and every other HST palette photo from now on!).