Free software like PixInsight's StarAlignment tool?

[VinnieM0nster]

Hi all,

I have trialled PixInsight but couldn't really get to grips with it so I've decided not to purchase it. However, there is one feature that I dearly miss now that the trial has run out, and that is its StarAlignment tool. It lines up the different RGB subs so that the stars overlap precisely, so that you can then combine them and start editing. Doing this manually in Photoshop is time consuming and error prone, because of field rotation.

Now my question is, is there any software out there that will do just the alignment, preferably at a low cost since I'm on a very tight budget!

Thank you!
Vinnie

[Guest]

DeepSkyStacker ( is a FREE SOFTWARE ) can also do Star-Alignment see here http://deepskystacker.free.fr/english/technical.htm                                                                                                                          

under Alignment .

 

Cheers

Martin

[VinnieM0nster]

2 minutes ago, artem said:

DeepSkyStacker ( is a FREE SOFTWARE ) can also do Star-Alignment see here http://deepskystacker.free.fr/english/technical.htm                                                                                                                          

under Alignment .

 

Cheers

Martin

Thanks Martin, but I've already got DSS, and while it works nicely for stacking and aligning subs of the same type (L, R, G, B or Ha, OIII, SII), it can't be used for what I want it to do. I want to keep the L, R, G and B stacked images as separate files, but all aligned to one of the other stacked images. Once they're all aligned I can then overlay them in Photoshop to create colour images. It's kind of hard to explain, so apologies if it's not clear.

Vinnie

[alexbb]

There's IRIS that can do this, sometimes it works, sometimes not.

DSS works only if the image scales are the same. So, if you refocus for each channel, there might be a "breathing" effect which changes the focal length too, therefore the scale too.

If the image scales are the same, you can open each set of subs (R, G, B, O3, S2) and open a frame (perhaps the best scored L or Ha) which you can set as the reference frame, but don't include in stacking (uncheck it). Then DSS will align all the frames with the reference one.

I also do this manually in GIMP (measure the distance between same 2 stars close to 2 opposite corners, scale, then align on one star and rotate) if the scales are different and IRIS doesn't work.

Moreover, I think IRIS also corrects some optical aberrations. The problem with IRIS is that many times fails to register the processed images. Maybe it works better with the unstretched images?!

Here are some other links that may help you, but I didn't test. If you find one that works better, please let me know as I'm interested too.

https://physics.stackexchange.com/questions/64180/aligning-images-of-starfields
http://www.astropix.com/HTML/I_ASTROP/SOFTWARE.HTM
https://www.reddit.com/r/astrophotography/comments/2acnqb/the_great_list_of_astrophotography_software/

I avoided and still avoid PI as I don't have enough time to learn this too, but eventually I will go this path.

HTH,

Alex

[r3i]

There's also Nebulosity - it's not free but the outlay is modest, though the current USD/GBP exchange rate admittedly makes it less of a bargain than it used to be.  This will align your images and create separate files for you to combine in whatever processing software you want.

It also has facilities to re-scale so that you can align images from different camera/scope combinations  - it's not as good as Registar at doing this and can take some coaxing to get it right, but it's workable if this is something that you do just occasionally.

[VinnieM0nster]

Thank you very much for your suggestions! I did not know that DSS could do what I wanted it to, simply by selecting the reference frame but then not including it in the final stack, that seems like an imminently logical way of doing this!

I knew I had to ask here, I've been searching for ages... I will give these suggestions a go over the weekend when I have some time, but in the meantime I just wanted to thank you for your help.

Vinnie

[The Admiral]

Likewise, AstroArt, that can be had from this site's sponsor. Not cheap, but then again, not as expensive as PI, and there may be features there that could be useful. I primarily use it for stacking. A demo version is available.

Ian