Gimp for astrophotos, tutorial

[Astrofriend]

Hi,
Have you noticed how advanced Gimp has been with the new version 2.10 ?

Now it work perfekt to open Fits 32 bit floating point images and process them. I have tried this many times earlier but it never worked very good. Now it's like a dream to work with.

I'm in the learning process how to use Gimp's capabilities. I have now got the opening process of three grey rgb images to work. It's of course not very complicated, but for me who never used Photoshop or something simular it was and I had hard to find a tutorial for the new version.

I have now made a tutorial for this first step how to start with Gimp and open 32 bits separated color images:
http://www.astrofriend.eu/astronomy/tutorials/tutorial-gimp-astrophotography/01-tutorial-gimp-astrophotography-introduction.html

If you already working with Gimp, have you found something of special interest ?

Lars

[RT65CB-SWL]

I admit it. I tend to be a cheapskate when it comes to software purchases.

GIMP and OpenOffice.org (and/or LibreOffice) are usually the first apps I download on my MS-Windows PC's/laptops. I was 'introduced' to GIMP and OpenOffice.org via Linux distro's (Fedora Core 1 and Mandrake 9.x) many years ago and have not looked back since.

I also have the MacOS X versions of the above apps; plus Stellarium and Celestia (again they are/were all free) on my Apple iBook G4.

Edited March 27, 2020 by Philip R

[Astrofriend]

When there are free tools it's always nice, especially when they work so well.

Today I did a background removal, it was not very difficult, look at page 4 how I did it with the Despeckle Filter in Gimp:

http://www.astrofriend.eu/astronomy/tutorials/tutorial-gimp-astrophotography/01-tutorial-gimp-astrophotography-introduction.html

 

/Lars

[RT65CB-SWL]

Excellent article @Astrofriend/Lars. 

[MarkAR]

Bookmarked the link, huge thank you.

[Anthonyexmouth]

On 26/03/2020 at 15:46, Astrofriend said:

Hi,
Have you noticed how advanced Gimp has been with the new version 2.10 ?

Now it work perfekt to open Fits 32 bit floating point images and process them. I have tried this many times earlier but it never worked very good. Now it's like a dream to work with.

I'm in the learning process how to use Gimp's capabilities. I have now got the opening process of three grey rgb images to work. It's of course not very complicated, but for me who never used Photoshop or something simular it was and I had hard to find a tutorial for the new version.

I have now made a tutorial for this first step how to start with Gimp and open 32 bits separated color images:
http://www.astrofriend.eu/astronomy/tutorials/tutorial-gimp-astrophotography/01-tutorial-gimp-astrophotography-introduction.html

If you already working with Gimp, have you found something of special interest ?

Lars

Maybe I'm being a bit dumb, but how do you open OSC fits images in Gimp? when i try i only get greyscale images. 

[Astrofriend]

Hi,

I shall try to explain, but what is  'OSC'  ?

/Lars

[JamesF]

7 minutes ago, Astrofriend said:

what is  'OSC'

"One shot colour" -- a colour camera rather than mono (requiring multiple "shots" to get a colour image, obviously).

James

[Astrofriend]

Ok,

I have three grey images, one for each color, sorry that it was not clear.

It came from a color DSLR camera that I demosaice the CFA image and then get these three grey images from. But that was not done in Gimp, it was done in the preprocess in AstroImageJ. After I have demosaiced the images I handled them as if they were from a mono chrome camera.

Sorry I was unclear.

 

/Lars

[Astrofriend]

The last thing I practise now are how to separate the stars from the DS. I got it to work, but used wrong parameters and got to big mask around the stars.

 

http://www.astrofriend.eu/astronomy/tutorials/tutorial-gimp-astrophotography/01-tutorial-gimp-astrophotography-introduction.html

 

I come back later.

 

/Lars

[Astrofriend]

Now I have earned more skills with Gimp. Got the selection around the stars better. I also changed my workflow to get it easier to do.

 

http://www.astrofriend.eu/astronomy/tutorials/tutorial-gimp-astrophotography/01-tutorial-gimp-astrophotography-introduction.html

 

Now I have to subtract the background of the DSO layer and increase the contrast of it. Coming back soon.

 

/Lars

[choochoo_baloo]

On 27/03/2020 at 16:51, Astrofriend said:

When there are free tools it's always nice, especially when they work so well.

Today I did a background removal, it was not very difficult, look at page 4 how I did it with the Despeckle Filter in Gimp:

http://www.astrofriend.eu/astronomy/tutorials/tutorial-gimp-astrophotography/01-tutorial-gimp-astrophotography-introduction.html

 

/Lars

Lars I want to thank you for such a generally useful and thorough website. It's great to have the mathematical/physics rigour for many topics.

I can see me spending many cloudy evenings trawling through all of these scholarly endeavours!! 🤓

[Astrofriend]

Hi Matthew,

Great to herar you find it useful, thanks for the comments !

I have done some small corrections:

http://www.astrofriend.eu/astronomy/tutorials/tutorial-gimp-astrophotography/01-tutorial-gimp-astrophotography-introduction.html

 

With Gimp I can do things that I couldn't do earlier. But earlier I was more concentrated to get high quality calibrated raws. But still my astro photos are taken from high polluted area. Maybe I can get my APO refractor more protable in the future and take it to dark places. My Raspberry project is one part of that.

/Lars

[Astrofriend]

I added a new Gimp tutorial, how to correct for optical vignetting:

http://www.astrofriend.eu/astronomy/tutorials/tutorial-gimp-astrophotography/01-tutorial-gimp-astrophotography-introduction.html

Now I can do more and more processing in Gimp.

 

/Lars

[Luke]

Hi Lars,

Thanks for making GIMP tutorials!

I have used Photoshop since 1999 I think (I've got the installer disc for version 5.5 still!) but I am out of work currently and a subscription to Photoshop is hard to justify! So I am switching to GIMP and other free tools, like Blender for 3D, Libre Office for spreadsheets etc. I actually prefer Calc to Excel!

It was difficult for me to switch to GIMP at first. I kept pressing Photoshop shortcuts (I am starting to assign the same ones in GIMP) and some things are done differently.

But I have to say, so far, I am really impressed. I am no longer capturing my own data and I am just starting to edit Hubble images. GIMP is handling a 7,000 x 7,000 pixels 16-bit file with multiple layers very nicely, on a mid-spec i5 PC (though my recent upgrade from 16 GB to 32 GB of RAM probably doesn't hurt for large images!)

 

I especially like:

- The GIMP curves editor - I love how I can make it as large as I like! I always wanted that in Photoshop.

- The free plugin G'Mic - https://gmic.eu/

I am only just starting to use the G'Mic plugin so don't know its full power but it looks to have multiple very useful things. I am already using its lovely sharpening tools. I can't wait to explore it some more! Split Details looks interesting - it can break up the details of an image into multiple layers, so you can then easily work on certain aspects of your image in isolation.

For my needs, Photoshop seems to be better for non-destructive editing, but that's a nice-to-have for me, not a critical thing. GIMP seems very powerful and I'm starting to feel more at home with it now. I may stick with it even if my financial situation improves!

Edited November 15, 2020 by Luke

[happy-kat]

This is a nice find post, I'll bookmark the site as I find GIMP a useful tool plus the plugins I already have like HLVG work.

Edited November 15, 2020 by happy-kat

[Astrofriend]

Hi,
I have some old photos of comets taken on film and to the first digital cameras I didn't have correct flat frames. I have used AstroImagesJ to make synthetic flat frames. But didn't work very well when the shape of the vignetting was too complicated. Then I took a new look at Gimp and what it can do. Found it to be very advanced and relative easy to correct the vignetting.

I added a new page on my Gimp tutorial how to do this:
http://www.astrofriend.eu/astronomy/tutorials/tutorial-gimp-astrophotography/14-tutorial-gimp-astrophotography-vignetting.html

Merry Christmas to you all !

/Lars

Edited December 22, 2022 by Astrofriend

[Astrofriend]

One rainy day I sat here with Gimp, I got dark pits behind my comets when doing darksubtraction. Testing a new method when I divide the Gaussian Blur filter to a two step process. Much better now.

Here how I did it:
http://www.astrofriend.eu/astronomy/tutorials/tutorial-gimp-astrophotography/13-tutorial-gimp-astrophotography-background-subtraction.html

/Lars

[Astrofriend]

Over the years I changed my how I work with astroimage editing.

 

Today I use Siril for pre processing (earlier I used AstroImageJ a lot), try to do all process which are closly related to stars before going over to Gimp for post processing.

https://siril.org/

The last thing I learned is how to color calibrate the images in Siril. When that is done it's much easier to handle the post processing in Gimp. I made a short notice about it on this page at bottom:

http://www.astrofriend.eu/astronomy/tutorials/tutorial-gimp-astrophotography/03-tutorial-gimp-astrophotography-levels-rgbload-rgbimage.html

I have also done some minor updates of the other pages. The combination of Siril for pre processing and Gimp for post processing is awesome.

I also use Irfanview, https://www.irfanview.com/

One important thing is that I can extract my Canon DSLR temperture with this software, I use the temperature in the file name, very practical when doing dark calibration.

http://www.astrofriend.eu/astronomy/tutorials/tutorial-darkframe-dslr-canon/tutorial-darkframe-dslr-canon.html

See note 2 how I rename the file name with temperature included.

/Lars

Edited March 13 by Astrofriend

[Ags]

 Thanks for the tutorials - I haven’t had time to go in details with them yet, but I have been looking for a Gimp Astro tutorial for years.