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M31 first meager attempt!


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Yes, you don't want to add the trailled subs to the stack. However, I'd recommend using kappa-sigma stacking mode if you have at least 12 subs - it's a statistical algorithm and does a great job of removing garbage from the final image provided you have some good subs in there. It also removes satellite trails, meteors and even aircraft lights blundering through the frame.

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Yes, you don't want to add the trailled subs to the stack. However, I'd recommend using kappa-sigma stacking mode if you have at least 12 subs - it's a statistical algorithm and does a great job of removing garbage from the final image provided you have some good subs in there. It also removes satellite trails, meteors and even aircraft lights blundering through the frame.

Should I use Kappa Sigma Clipping for my Lights and Bias shots? And for Darks and Flats too if I create some?

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Wow thanks AG, fantastic job! How did you manage to get rid of all the stuff above M31? Whenever I managed to bring M31 out a bit, the rest of it came out too, causing it to look like a dome.

Also, could you give me an idea of what you did? Then maybe I could try to recreate something similar, which would no doubt teach me a lot. And what software did you use? If it was a paid product like Photoshop, would I be able to produce something similar in GIMP?

Also I'll check the frames today.

You are welcome, I used Pixinsight and finished it in Photoshop so unless you are familiar with the software you wouldn't relate to the steps but I will list them for interest. I am afraid that Pixinsight is a relatively expensive and complicated piece of software.

a: Dynamic  Crop to centre the galaxy

b: Dynamic Background extraction in two step, subtraction and division.

c: Background neutralisation

d: Colour Calibration taking the Galaxy as " White reference "

e: Histogram Transformation using the STF default parameters ( this is the stretching stage where the data in no longer linear )

f: A very conservative HDR wavelet treatment using 6 layers with lightness masking

g: A slight colour saturation using Curves transformation and a mild noise reduction using ACDNR tool

h: Import into PS as a Tiff file

I : Two passes of the Gradient Xtermintor filter to further flatten the background with the galaxy masked off

j: Dynamic enhancement of the Galaxy

k: Applying the selective colour tool

l: Noise reduction to the low signal level areas

m: A single pass of the HLVG ( this filter is a free download ) to remove any green cast

n: Downsizing and saving as PNG

As mentioned I did not do any of the usual Pixinsight involved processing stages other wise I would still be at it. To see how Pixinsight could be used in simple terms the best bet is to use the tutorials by Harry at Harrysastroshed.com and you can also request a trial licence of Pixinsight which is fully functional including the save functions for fourty days from Pleiades Astrophoto.

Hope this helps.

Regards,

A.G

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Impressive stuff, and unfortunately complex too! And also expensive if I were to buy Pixinsight, as excellent as I'm sure it is.

Here is the stacked TIFF with all 9 star trail reject shots removed:

https://www.dropbox.com/s/gefy7jtln3vzjvr/DSS%20Stacked%20M31%20No%20Star%20Trail%20Subs.TIF?dl=0

I also use StarTools. This is not as complete a package as Pixinsight but for processing it is not far off at a price comparable to a Photoshop elements perhaps. You may wish to give it a go. The trial version is fully functional but the save function. I am afraid that unless you have a decent processing software you may not be able to extract all the information from your data into an image.

regards,

A.G

A.G

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Great work! As for postprocessing I can give You only a bit of advice. My workflow includes saving the basic DSS output, then flattening the gamma curve (under Luminance tab) and levelling the color intensity (Your picture shows it is already in place) and then saving again. Afterwards I use Gimp (too bad it allows only 8bit per channel), usually with the second picture, and tweak the histogram to achieve darker background. Then I adjust the colors, brightness and contrast - it's usually trial-and-error for me.

However, I'm sure You can bring a lot of Your picture - just look at my effort of M42 (subs looked similar).

attachicon.gifM42, raw, 10+8 images, cropped.jpg

Did you do that with DSS and GIMP? And could I see a JPEG of your stacked TIFF to compare?

I'm keen on knowing how much can be done with GIMP. Clearly it looks like Pix is the best option, but it's also an expensive commitment.

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I also use StarTools. This is not as complete a package as Pixinsight but for processing it is not far off at a price comparable to a Photoshop elements perhaps. You may wish to give it a go. The trial version is fully functional but the save function. I am afraid that unless you have a decent processing software you may not be able to extract all the information from your data into an image.

regards,

A.G

A.G

50 Euros is a great price for StarTools (I'm sure Pix was about 200 Euros or something). And with the demo I could see what it can do (or rather what I can do with it) before comitting to buy. I'm guessing that I'll need to download the 32-bit version, as I only have a Lenovo X200s laptop with 4GB RAM. Well, that and a desktop PC, but the PC is even older and slower,

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I had a go with your second stacked version, again with Pixinsight, below:

post-30803-0-43002800-1417968914_thumb.j

The stars look a lot better now, but as A.G said, there is a stubborn band of lighter stuff along the bottom edge of the frame that's hard to get rid of satisfactorily without affecting the galaxy.

When you're shooting, make sure the target is nicely centered in the frame away from any problem areas on the sensor.  Also, you might find that when you take dark frames, that they exhibit the same band, which will be a good thing since if so, they'll get subtracted from the image when you stack it.

I think the thing that was stopping you getting a good post-processing effort yourself was the vignetting (darker edges, lighter middle), so I've uploaded a tiff where I've just done the background gradient removal and nothing else - have a go with this file, you might find it easier to process.  https://www.dropbox.com/s/0x4xp1n78iz2a90/DSS_Stacked_M31_No_Star_Trail_Subs_DBE.tif?dl=0

I did that gradient removal with DBE in Pixinsight.  The Gradient Xterminator plugin for Photoshop does similar.  There are manual ways of doing it that you may be able to do in GIMP but they are rather long-winded and I can't remember how to do them, you may find suitable tutorials on the web.

edit:  hmm, the posted jpg doesn't look as good as the fits I have, bit of background colour blotch going on there.  Ah well

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50 Euros is a great price for StarTools (I'm sure Pix was about 200 Euros or something). And with the demo I could see what it can do (or rather what I can do with it) before comitting to buy. I'm guessing that I'll need to download the 32-bit version, as I only have a Lenovo X200s laptop with 4GB RAM. Well, that and a desktop PC, but the PC is even older and slower,

The last time I tried the 32-bit StarTools wouldn't work with dslr-sized images (under 32-bit Windows ), unfortunately. I think it needs more memory than can be provided on a 32bit/4Gb system.

Louise

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50 Euros is a great price for StarTools (I'm sure Pix was about 200 Euros or something). And with the demo I could see what it can do (or rather what I can do with it) before comitting to buy. I'm guessing that I'll need to download the 32-bit version, as I only have a Lenovo X200s laptop with 4GB RAM. Well, that and a desktop PC, but the PC is even older and slower,

The 64 bit will work with win  7 64 and 4 gig of ram, the 32 bit will not see more than 3 gig. I use an i5 thinkpad with 16gig and it is fine there.

A.G

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I had a go with your second stacked version, again with Pixinsight, below:

attachicon.gifM31.jpg

The stars look a lot better now, but as A.G said, there is a stubborn band of lighter stuff along the bottom edge of the frame that's hard to get rid of satisfactorily without affecting the galaxy.

When you're shooting, make sure the target is nicely centered in the frame away from any problem areas on the sensor.  Also, you might find that when you take dark frames, that they exhibit the same band, which will be a good thing since if so, they'll get subtracted from the image when you stack it.

I think the thing that was stopping you getting a good post-processing effort yourself was the vignetting (darker edges, lighter middle), so I've uploaded a tiff where I've just done the background gradient removal and nothing else - have a go with this file, you might find it easier to process.  https://www.dropbox.com/s/0x4xp1n78iz2a90/DSS_Stacked_M31_No_Star_Trail_Subs_DBE.tif?dl=0

I did that gradient removal with DBE in Pixinsight.  The Gradient Xterminator plugin for Photoshop does similar.  There are manual ways of doing it that you may be able to do in GIMP but they are rather long-winded and I can't remember how to do them, you may find suitable tutorials on the web.

edit:  hmm, the posted jpg doesn't look as good as the fits I have, bit of background colour blotch going on there.  Ah well

Thanks for that. It would seem that the version of the TIFF without the star trail subs provides better results. And I can get similar results in GIMP to the jpeg you posted, so the gradient removal made a big difference. I'm guessing there is no such plugin for GIMP! In which case maybe a version of Photoshop and that plugin might help.

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The problem is I kind of feel like I've cheated when someone else has processed it for me :tongue: Does anyone else think like that if someone else helps process the image?

When it comes to image processing, are there any paid programs which allow for older machines? The laptop is the best I have at the moment, although it doesn't seem to have a problem with processing in GIMP, so I wonder if they may be other programs out there, or maybe just older versions of Photoshop or something maybe. I suppose it all depends on whether there were major leaps in terms of astronomical-process features since those older versions or programs were around.

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The problem is I kind of feel like I've cheated when someone else has processed it for me :tongue: Does anyone else think like that if someone else helps process the image?

I'll let you have that background-flattened tiff for free.  Waiting for you to produce the definitive final version though   :grin:

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I think AG has outdone anything I could produce to be honest! But then I do have the excuses of a lack of experience and an inferior computer and software!

But that TIFF you produced is definitely easier to work with in GIMP. If I had software that could do whatever it was you did with it then that would certainly help.

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I also use StarTools although as I'm on a 64 bit OS I haven't come across any memory problems. I'm still learning my way around it but it seems to be great value. Pixinsight is very well regarded but it seems to require an investment in time as well as money. I did look at the demo once but was left scratching my head.

I can't recommend GIMP for astro processing I'm afraid as it only supports 8 bits per channel, so you'd lose data when making adjustments. There is 16-bit support in beta but I've heard there are some problems. I'm using an old version of Photoshop (CS2) at the moment which was very cheap.

Aha so you don't know everything :tongue:

There's an awful lot I don't know, especially when it come to processing. ;)

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I also use StarTools although as I'm on a 64 bit OS I haven't come across any memory problems. I'm still learning my way around it but it seems to be great value. Pixinsight is very well regarded but it seems to require an investment in time as well as money. I did look at the demo once but was left scratching my head.

I can't recommend GIMP for astro processing I'm afraid as it only supports 8 bits per channel, so you'd lose data when making adjustments. There is 16-bit support in beta but I've heard there are some problems. I'm using an old version of Photoshop (CS2) at the moment which was very cheap.

There's an awful lot I don't know, especially when it come to processing. ;)

Yeah it seems to me that CS2 Photoshop or similar might be the best option for me at the moment, in terms of both money and what my computer can manage. Will have to look into it.

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cs2 can only be downloaded for free if you wish to reinstall. If you do otherwise it's illegal and as such can not be discussed on sgl

thankyou.

I'm sure one of the more informed moderators will be along to explain it better

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